Ergaea walshi (Reeve), a symbiotic calyptraeid inhabits inside of gastropod shells used by hermit crabs. We report E. walshi preserved in gastropods from the Upper Pliocene–Lower Pleistocene (Piacenzian–Gelasian) Takanabe Formation and the Middle Pleistocene Toyohashi Formation. These autochthonous occurrences of E. walshi are an exceptional fossil record from the Pliocene–Pleistocene of Japan.
https://ror.org/0375k5p31 
