What rolls like an armadillo but lives in the sea? This is a question asked in a recent New York Times article about the lowly chiton. Half-a-billion years ago primordial trilobites first demonstrated the ability to roll themselves into a ball. Their modern day doppelganger is the mollusk we call the chiton. This defense mechanism, called conglobation, is used by animals as varied as armadillos, pill bugs and hedgehogs. The thrust of this article is that the chiton is not as simple an organism as first supposed, but being top heavy, not all that flexible and lacking appendages, the chiton has difficulty righting itself when flipped over. It is thought that in addition to defense conglobation also provies these organisms a means of locomotion. Allowing them to roll to a new perch to attach upon.
I took this photo while tide-pooling this summer in Oregon. It was early in the morning and in the middle of one of the lowest of low tides that normally occur around a full moon. We walked on dry land, on a sandy beach that is normally covered in sea water over our heads. We were in fact walking on the bottom of the sea. We could walk up to rock outcroppings like the one pictured and view a large assortment of sea beasties like this chiton.