From the ‘things that make you go hmmmm” department: behold the sand-grain house built by Difflugia coronata, a single-celled amoeba with no nervous system:
Some further information from Mike Hansell’s book Built By Animals (Amazon US and UK):
How does this single-celled creature build such an elegant house? Well, we don’t really know. The only information we have at the moment is a description of what we can observe. An individual Difflugia flows around, carrying its case with it. While doing this, it not only engulfs food particles but also tiny sand grains that accumulate inside the amoeba as a large ball. When the time to reproduce arrives, the nucleus of the amoeba replicates its DNA to create two complete nuclei. The cytoplasm (the body material) then begins to divide, one nucleus going into each half, to form two independent organisms. One of these will inherit the existing house, but the other takes the ball of stones in its cytoplasm. As the two organisms are created, these stones move to the surface and arrange themselves as a new house.
That last sentence may sound pretty unsatisfactory. It is like a magic trick that leaves you wanting to know how it was done rather than simply enjoying the moment, but we simply don’t have the information.
Funny thing is, I’m sure both IDers and Darwinists would see this organism as being supportive of their worldview.