Two realms of objects
Gestalt psychology once emphasised the fundamental difference in the phenomenology of natural objects and artifacts. So as not to assume any particular metaphysical implications of these, we might rather say that there is a fundamental difference between discrete single objects as typically examplified by artifacts on one hand, and non-discrete objects as typically examplified by natural objects. So, artifacts are usually discrete, easily distinguished from each other, usually geometrically regular (or more or less complex assemblies of individual geometrical units), usually brightly coloured, easily sorted, stacked, and counted; they can be understood teleologically, in terms of intended function. Natural objects are usually the opposite: usually merging together, difficult to separate from each other and to understand the individual units among, indeed quite ambiguous in such ontological terms, and furthermore typically geometrically irregular and with heterogenous and often diffusely blending colours, unintelligable in terms of intended function without advanced theories (either a "secondary teleology" through a functionally focused adaptationist evolutionary biology, or theism).
Of course this is by no means a sharp border, there are several untypical objects from both sides. Every archaeologist will complain that it can be very difficult to separate artifacts among natural-looking objects. And there is nothing stable about them. Things are pulled out of the diffuse logical flow (in this sense "natural") and transformed into artifacts by slight manipulations and sometimes by this act of choice and removal out of original context itself. An obvious example is how shells, beautiful stones, interesting roots, dead insects, skeleton parts, etc, are picked up, collected and transformed into aesthetical and occasionally scientific objects, and how fruits and other plant parts as well as dead animals are picked up as food items. On the other hand, discarded and abandoned artifacts enter the sphere of unseparable natural objects; littering and ruins. In a sense, art is a big endeavour to create artifacts with the opacity of natural objects, which will be able to produce meaning far beyond the simple statement of their intended function, in a way that simulates or indeed becomes nature.
The distinction approximately corresponds with that between indoors and outdoors environments. An indoors environment is one intentionally structured, usually geometrically arranged, dominated by artifacts and their rational arrangement for a purpose. Outdoors is structured by other factors than reason and intelligence, and is dominated by natural objects - though in many cases, such as cities, baroque gardens, and agricultural fields, there will indeed be a superimposed artificial and gemetrically regular structure, but however one which will be immediately subverted by the action of weather, plants and animals; there will be leaves, twigs, dust and seeds moving around, snow and pools of water, emerging plants and mushrooms, as well as a more or less rapid weathering and irrational rearranging of the artifacts through the actions of weather, irresponsible or responsible humans, as well as by other animals and plants of course.
It seems like the ambiguity and transition in this respect has often been interesting to surrealists. The transformation of natural environments into manifested projection spaces for the imagination have often aroused a great interest; brut architecture, utopian city planning, theme parks, park planning, japanese gardens, futuristic visions, have all had their share of attention (often including suspiciousness) from surrealists. So has, and far less ambiguously so, that which moves in the other direction in the relationship, becoming secondary nature: ruins and abandoned environments, worthless places, vast ruderal areas, junkyards.
And a special polemical case in this very matter is the category of surrealist objects. Surrealism takes objects out of their functional context and allow them to develop a natural-like semantical richness. The shared component in all surrealist objects is that they have been made poetic objects by having been taken out of their given context and allowed to develop a network of relationships, associations and determinations that are unrestricted by functional context. Then for the artifact-type objects this means more to take them out of utilistic context, and for natural objects to take them out of natural context. However, in both cases we must take care not to fall in the trap of establishing a new quasi-functional concept based on aesthetics in the narrow sense and/or anecdotal/selfbiographical sentimentality. Those objects which are put on a piedestal for being beautiful or for reminding someone of a beautiful event or period in life are only "liberated" in a weak sense, they are transposed into another utilistic context, less restricted for sure, and since that particular purpose is largely conditional and focused on a subjective level (also where the objects are marketed as commodities) they often have occasion to transgress it. Because it is only when they are allowed to be "worthless", to be isolated and reconfigurated without particular goals, that they can develop quite new unexpected relationships and insights. This state is far easier attained in an unordered accumulation of curiosities, or in a playful assemblage, or in a crowded exhibition, than when tastefully displayed with appropriate margins and spaces, but its not impossible among conventional aesthetical objects, nor in conventional art, or low-brow home decoration in general, nor by chance in the toolshed, the cellar, or even the marketplace.
Natural objects, merged as they are in the environment, are mostly in a sense asleep: associatively, imaginatively, symbolically, communicatively – and remember that these four aspects are all different, even though they partially overlap with each other. Bringing them out of context is a way of stirring them to wake them up, and it may be to an existence in slavery under some practical work task, or in tragical-pregnant isolation stretching out to establish relationships in all directions... Surrealist objects lie around longing for their freedom, planning for it, and occasionally allowing us to catch a glimpse of it, everywhere.
I hope I don't have to say that it would be absurd to interpret these distinctions in terms of value; all different modes of being an object are perfectly legitimate ways of being an object. Of the two sleeping modes, the artifacts are characterised by their straightforward rational use value for us, and the natural objects by their non-rational use value for themselves (which may seem excitingly alien to us). The awakening mode, the objects released from utilistic connections from either camp, assumes a poetic use value, for themselves but in complicity with us.
If we are nowadays rather immune to the danger of getting dazzled by the artifacts after progress and rational solutions proved to be of limited application, there may still be an obvious risk of romanticising natural objects simply by being inexperienced with them and remaining uninformed about them: they may all seem so admirably inhuman, irrational and free for anyone who has no analytical tools for observing patterns in nature and thus keeps missing their modes of connection, modes of repetition, modes of labor, modes of economy, modes of utilism; such a person would believe every natural object encountered will be in itself free of determinations and thus a surrealist object. But of course, that person is likely to mostly stay in the city or at least not look very carefully around, in order to maintain that strange bias where only artifacts are typical objects and all natural objects are strange harbingers of a hidden world of wonders. It would be alien to me to suggest that natural objects are not interesting, exciting and beautiful objects in their capacity of natural objects, their own utilistic connection, (which is partly about their negating the artifact mode of utility and partly about aesthetical and psychological response to their general morphology, their organisation principles, their visual signals, etc) - but still that is what exactly what has to be superceded to make them surrealist objects rather than either scientific objects, aesthetic objects, objects of mere wonder and entertainment, or natural objects in their own right. I am talking about where they too are taken out of context. And this does not mean the vast sphere of antropomorphising, to regard the facial expressions of animals, the atrocities of insects, the mysterious behaviors of plants, as mere jokes for their unfettered variations of human analogues. I am talking about new and poetic contexts, where they may or may not evoke wonder or associations to their lifestyles and evolution, may or may not evoke transgressions of the notions of the human, but regardless of whether they do or not, remain open to establish new connections. Releasing them from their utilistic connection simply by stubborn ignorance of it is a very fragile form of liberation; it not only demands the same ignorance and non-familiarity of every observer, but tends to nivellate and therefore in the long term depreciate the whole world of natural objects.
Just like the poetic use of a shoe seems to presuppose observing the very transcendence from being a vehicle for containing feet and separating them from the possibly hostile ground into something else, and would not be the same thing for someone who had never considered using shoes; in the same way the strange shape of a mushroom will be a carrier of poetry rather than of superstitions when it is first understood and then abandoned that it is a mere temporary sexual organ of the fungus body interweaving the ground, and its sudden appearance comes from a very determined structure of chitine growing fast by absorbing very much water but then manifestating that structure only in an irregular form exactly conforming to the temporary configuration of the surrounding - now all of this is perhaps a bit mysterious indeed, but if we are excited about that, we are excited about the life of fungi, which biology has far more to teach us about than poetry has. There is a sense of wonder about a mushroom which simply does not depend on whether one associates to the particular forest habitat where it grew or not, whether one knows how it tastes or not, whether one has seen hundreds of mushrooms like it or not, whether one knows about the sexual mysteries of fungi or not, etc - and it is only when that particular sense of wonder is succesfully invoked that the mushroom becomes a surrealist object, a "liberated object", rather than an object of exoticism.