This week, we’ll look at another marine living fossil – clam shells. Their proper name is a ‘bivalve’, because of the two (bi) halves (valves) they have. These shells are common around our beaches today, you may even enjoy collecting them! They are living fossils because they have not changed since they first appear in the fossil record – they have remained completely unchanged.
We can learn other things from these fossils as well. If you’ve ever collected shells on the beach before, you will know that most of them are in halves. This is because the two halves are joined together by a hinge in the shell, which is held tight by a ligament. Once the clam dies, the ligament very quickly rots and falls off, and the two halves fall apart.
However, in almost every instance, these fossil clams are shut! Swept into place in their thousands, they are all still tightly closed, meaning two things:
- These clams were buried while still alive,
- These clams were caught up and buried extremely quickly, before they had time to open up and rot after dying.
These clam shells can be found in huge deposits, with millions of clams in a single area. A very powerful testimony to the fact that fossils not only have been buried quickly, but also have to be, in order to exist in the first place.