Though scientists have long believed that
complex organic molecules couldn’t survive fossilization, some
350-million-year-old remains of aquatic sea creatures uncovered in Ohio,
Indiana, and Iowa have challenged that assumption.
The spindly animals with feathery arms—called crinoids, but
better known today by the plant-like name “sea lily”—appear to have been buried
alive in storms during the Carboniferous Period, when North America was covered
with vast inland seas. Buried quickly and isolated from the water above by
layers of fine-grained sediment, their porous skeletons gradually filled with
minerals, but some of the pores containing organic molecules were sealed
intact.