Bivalve shell and wood
Floating to freedom…for a while
These bivalve mussels were attached to the wood by ‘byssi’ (strong threads). However, sooner or later the wood became waterlogged or the colony of bivalves grew too heavy for it, and the whole lot sank to the sea bed. The sea bed was a stagnant and anoxic (low oxygen) place, so the bivalves would have perished quickly. The upside is that, as a result, the bivalves and log became very well-preserved.
Find out more about bivalves on the molluscs pages.