1. Trivia monacha adult shell cut open to show internal coiled juvenile shell. A very small rise on the outer adult shell indicates the position of the enveloped juvenile spire apex. LWS, Scapa Flow, Orkney Sept. 1975
2. Trivia monacha adult shell cut open to show internal coiled juvenile shell. A very small rise on the outer adult shell indicates the position of the enveloped juvenile spire apex. LWS, Scapa Flow, Orkney Sept. 1975

Trivia monacha adult shell cut open to show internal coiled juvenile shell. A very small rise on the outer adult shell indicates the position of the enveloped juvenile spire apex. LWS, Scapa Flow, Orkney Sept. 1975