Some do and some don't. Mammals, for example, must mate in order to reproduce. Other animals, such as certain kinds of sea-sponges, can reproduce asexually.
Sponges reproduce by having sex with their mate [conjugation] and making baby sponge Eggs that will touch Rock and stay on there for a few weeks until they can move and get their flagellas. Glass sponge does not appear in The Index.
No, sea sponges are not decomposers. Sponges are filter feeders.
no sponges are not unicellular.
No, sponges are not parasitic.
no sponges do not have bones
Sponges are asymmetrical, although a few species have nearly radial symmetry.
Yes sponges have organs.
No. Sponges are animals, which are heterotrophic.
To answer your question no sponges do not hibernate
No sponges lack organized multicellular organs, such as nerves and muscles.
porifera are also called sponges some of the sponges are euplectelia spongilla and sycon