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Discinacea(order Acrotretida, suborder Acrotretidina) A superfamily of inarticulate brachiopods, in which growth of the pedicle valve occurs all around the edge and the valve is usually conical to subconical. The phosphatic shell is homogeneous, finely punctate, and not in alternating organic and phosphate layers. All recent species are shallow-water forms, except one which is abyssal in habitat. The Discinacea appeared first in the Ordovician.