The sponge is a member of the phylum Porifera. It is a multicellular primitive mammal, however, it is devoid of a mouth, muscles, a heart, and a brain. It cannot move around as most species can since it is sessile. Animals that only thrive in a single location, like most plants, are sponges.
Stinging cells, a phylum of Cnidocytes, or "stinging cells," are specialized neuronal cells that are only found in the order Cnidaria (sea anemones, corals, hydroids, and jellyfish).
These cells include the cnida or cnidocyst organelle, which is the product of massive Golgi discharges.
Tissues are missing. In that they are heterotrophic, multicellular, lack cell walls, and produce sperm cells, sponges share characteristics with other animals.
They don't have actual tissues as other animals have.