There are Myophorella clavellata and Gervillia bivales on this block. Notice how all of the shells are lying in the same orientation. This suggests that a strong current was flowing across the sea bed when these animals became buried. Convex shells tend to flip over with the curved face uppermost as this is a more stable angle than the other way around. This is known as a ‘way up structure’ and can be really useful in mountain ranges where earth movements have folded the rocks so extremely that they might be upside down.
Find out more about bivalves on the molluscs pages.