Jurassic Period, 160 million years BP. A polished fossil Rastellum carinatum bivalve shell. 190 grams, 92mm (3 1/2"). From an old Bristol paleontological collection; from Tulear Province, Madagascar. This bivalve is from the oyster family and it has wide, angled ribs that have led to it being called the 'denture clam; the zig-zag join between the two shells stopped coarse dirt and debris entering the shell and damaging its soft body; like modern oysters, it lived in shallow coastal waters including the intertidal zone and fed on food particles that it filtered out of the sea water. [No Reserve]

Very fine condition.