in Cymbuliidae the calcareous shell is lost and replaced by a permanent cartilaginous-like, slipper-shaped organ: the pseudoconch. Lalli and Gilmer (1989) also described pseudoconch formation in Euthecosomata but it seems not to be a permanent structure in this group.

Alternative forms for pseudoconch : pseudoconcha, pseudoconchae, pseudoconchs, slipper, slippers, [p][/p].