Demosponges have siliceous spicules and a network of fibrous protein, spongir, that is similar to collagen. The demosponges are the source of natural household sponges, which are made by soaking dead sponges in shallow water until all the cellular material has decayed, leaving the spongin network behind.

And woods along the banks are waving high, / Whose shadows in the glassy waters dance,

Random amorphous bits of fired clay, temperless and not identifiable as wall daub, were frequently encountered in the excavations.

You still think they come all boxed, sorted, and labeled, do you? he said. And that they aren't ‘just folks’ at all? Yes, I still think so. They never seem a bit like ‘folks’ to me. It's their business to sit up there stiff and solemn and stern.