The porifera and coelentera . cases it must be considered as a normal featiue of certainspecies (Evans, 1899). Union between the spicules is effected either by means offibrous tissue or by spongin.
Phylum - Porifera (Sponges)
Phylum Porifera (Sponges)| Characteristics and Examples of Phylum Porifera | Animal Kingdom