Lingulid brachiopods have an extremely long fossil record, which stretches back into the Cambrian Period, more than 500 million ago, and belong to one of the oldest families of multi-cellular animals known to science.
Since their origins, these creatures have remained fairly unchanged, and they still survive roday in the deep sea, earning them the nickname 'living fossils'.
Lingulids became fairly diverse during the Cambrian Period bur went inro decline during the following Ordovician Period and have never since been a varied group. Lingula itself is a relatively small inarticulate brachiopod (one that lacks a hinge to hold the two valves together).
Its valves are thin, biconvex (both bulge outwards) and tongue-shaped in
outline, lacking strong ornamentation.
Today's Lingula lives buried in sediments along the shore's inter-tidal zone, and is
eaten as a delicacy in some parrs of South East Asia.
The lingulid shell is made of protein, chitin and calcium' phosphate