Stauractura = Cruciform shell with four rays; σταυρός, ἀκτίς, ὀυρά.
Pentactura = Stellated shell with five rays; πέντε, ἀκτίς, ὀυρά.
Echinactura = Echinus-like shell with five rays; ἐχῖνος, ἀκτίς, ὀυρά.
Archidiscus = Primordial disk; ἀρχιδισκος.
Axodiscus = Disk with certain axes; ἄξις, δίσκος.