Critter of the......evening. Liebea.

This is Liebea, a Permian bivalve mollusc similar to modern mussels. They were epibyssate suspension feeders, meaning that they anchored themselves to rock or seaweed and filtered food particles out of the water. Liebea  commonly formed clumps containing only that species.

The fossil above is Liebea squamosa  and is one of the bivalves I found in the Ashfield Brick-clay Pit in Conisbrough. Like the brachiopods found there, the Liebea  fossils appear to be quite small (about half the size they should be) but not to the same extent as the brachiopods. This could be interpreted as having a high infant mortality rate (due to overcrowding or a soft substrate) or small adult size due to overcrowding.