Give the general characteristics of phylum porifera.

The characteristics of phylum porifera:
(i) Porifera includes sponges.
(ii) They are multicellular.
(iii) They are aquatic and mostly marine.
(iv) Body cells are arranged in two layers.
(v) Inner layers have flagellated collar cells.
(vi) Nervous system and organs are absent.
(vii) Skeleton consists of spicules.
(viii) Canal system is always present.
(ix) Reproduces both asexually and sexually.
(x) Larva is ciliated.