Hemidiscellidae
Hemidiscellidae is an extinct family of sponges in the class Hexactinellida and the subclass Amphidiscophora. Hemidiscellidae is the only family in the order Hemidiscosa.
Hemidiscosans are differentiated by the form of their microscleres. Their microscleres, more precisely known as hemidiscs, have the form of a rod with a large umbel at one end and a much smaller umbel on the other end. This form of microsclere is intermediate between paraclavules and amphidiscs.