Bivalve (clam) shells found in Summer 2010 were the first body fossils found in the Cantwell Formation. Clams could live in freshwater or ocean water and lived on the surface or burrowed into the soft, muddy bottom.
Snails and insects made little tracks in the mud when they moved across the surface. Some of these tracks were preserved and look like wavy lines, as seen on the rock slab above.
Many animals dig into soft mud or lake bottoms to escape predators or find food. It is very hard to figure out what type of animal created a fossilized burrow, but clams, snails, and many other small creatures could make burrows.