1) Member of the calcarea class 
Sycon is a genus of calcareous sponges belonging to the family Sycettidae. These sponges are small, growing up to 7.5 cm and having length from 2.5 to7.5, and are tube-shaped and often white to cream in colour. Species in this genus include: ...
(from the article `sponge`) ...expelled (excurrent system). Three types of water-current systems of increasingly complex structure may be distinguished by the arrangement of ...
Sycon is a member of the Calcarea class.
a type of sponge having a thick body wall that is folded to form many short canals leading to the spongocoel. Cf.