Phylum Porifera includes three classes, chiefly based on the type of its skeleton. The skeleton of some sponges are utilized for many purposes such as washing, bathing, scrubbing, mopping etc.
Some of the common sponges belonging to the three classes: Calcarea, Hexactinellida and Demospongia.
1. Class Calcarea characterised by limy spicules.
Example: Leucosolenia, Scypha, Grantia.
2. Class Hexactinellida with six rayed siliceous spicules.
Example: Euplectella (Venus’s flower basket), Hyalonema (Glass
3. Class Demospongia with a skeleton formed of siliaceous spicules and sponging fibres.