Classification of Phylum $Porifera$ is based on

What remains when bath sponges dry up?

Which of the following is the larva of Porifera?

Which phylum is characterized by a body with an internal cavity lined by food-filtering flagellated cells (choanocytes) and indirect development?

Animals of this phylum are multicellular but exhibit cellular level of organization.

If a food particle is placed near the ostia of a sponge,what will happen?