Animal is globular, about 0.5 in (10-15 mm) in length, translucent white, with a small wedge-shaped, fragile, permanently gaping internal shell covered nearly entirely by external mantle folds. Anterior cowl is wide and flaring; there are two long retractable anterodorsal "cephalic" tentacles and a single short pallial tentacle next to the excurrent siphon on the posterodor-sal midline. The foot is large and muscular with an elongated narrow posterior portion used in byssal attachment and "hanging" behavior. There are three to seven sensory flower-like organs on the visceral mass near the mouth.
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