Bivalve Fossils Bivalves appear in the fossil record first in the early Cambrian more than 500 million years ago. Bivalves as a group have no head and they lack some usual molluscan organs. The shell of a bivalve is composed of calcium carbonate, and consists of two, usually similar, parts called valves. These are joined together along one edge (the hinge line) by a flexible ligament that, usually in conjunction with interlocking "teeth" on each of the valves, forms the hinge. This arrangement allows the shell to be opened and closed without the two halves detaching.
Mazon Creek invertebrates A Miscellaneous mix of Arthropods, Bivalves, Jellyfish and Worms/Shrimps. All are from the famous Mazon Creek Beds, and 307 Million years old
Rastellum "Alien" carinatum bivalves Rastellum carinatum is a Cockscomb Bivalve from Northern Madagascar and is Cretaceous in age. Has a typical bivalve zig-zag appearance of where the two valves shut. Found in Marovoay, Mahajanga district. Many people call these "Aliens". Size is typically 70-90mm on average, see the photo for scale
Shell Jasper from Madagascar Shell Jasper, cut and polished rock slices. This is full of sea shells, the fossilized remains of bivalves and gastropods. It has really great contrast. Found in Madagascar. Makes a great display.
Gryphaea (Devil's Toenails) from UK Really the best grade you are going to find of these curious folklore fossils. Gryphaea obliquata was a marine bivalve mollusc. These all come from Monmouth beach, Lyme Regis. They are dated to around 200 Million years old. Each one is photographed so that you will hopefully be able to see the scale and size. These are clean and have a natural polished lustre given to them by nature. All we do is give them a little dry brushing and that's it.