The mantle edge is thickened by large, inflated, puckered, connective tissue cells (1) blocking the entrance to the mantle cavity, except for the inhalent (2) and exhalent (3) passages.
When in motion on a flat surface, the unstippled white sole is ovate with a constriction (4) close to the broadly curved anterior shaped like an axehead with flexible corners. The foot readily folds (5) transversely at the constriction.

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