Porifera and Cnidarians Porifera and Cnidarians Phylum Cnidaria-have cnidocytes, or stinging cells, as well as having radical symmetry. They have two forms, polyps and medusa. Many cnidarians alternate between these forms, but others, such as corals only occur in polyps. Each cell in a sponge is responsible for eating, no mouth or gut, sponges are colonial. Collar cells are the work horses of the sponge.
Sponges have spicules, which are secreted by the amoeboid cells.
These are made of silica or Calcium Carbonate. Contrary to popular belief, few sponges are soft like bath sponges.