The Polished Paper Mussel
A member of the Mussel family Mytilidae, the Polished Paper Mussel, Arcuatula papyria (Conrad, 1846), is an elusive local species that happens more abundant in nature than its relative obscurity and scarcity in local collections would lead us to believe. One of the reasons for its status as a poorly known species is that it lives burrowing in the muddy bottoms of local bays and protected back waters, in areas that are difficult to reach and almost impossible to walk on due to the plastic, very soft nature of the mud. Another reason is that Polished Paper Mussel shells are extremely thin, breaking almost immediately after the mollusk dies. Nonetheless, it is a very elegant pale green shell, semi-translucent shell, internally with faint hints of mother of pearl (nacre).
Photo on top shows inside of shell, bottom view shows outside surface. Photos by José H. Leal.