Crinoid sea lily
This crinoid, called Pentacrinites, lived attached to driftwood floating in the Jurassic sea. When the wood became waterlogged, or the colony grew too heavy, the whole lot sank to the sea bed and became fossilised. In this specimen, the individual crinoid stems are orientated in the same direction, suggesting that the wood was originally located beyond the bottom of the picture.
Find out more on the echinoderms page.