1. They are the simplest multicellular organisms and are immobile.
2. Their body wall has numerous openings called ostia.
3. The body contains flagellated cells called koanocytes.
4. The body has a cavity called spongocele or paragastric. Each spongocele has a single pore called an osculum.
5. The body does not have well-organized organs, organs or systems.
6. They have a duct system in their body. There are three types of canal system. Ascon type, cycon type and leucon type. It functions in respiration and water flow.
7. Endoskeleton composed of spicules or spongy fibers. Spicules are composed of lime and spongy collagen proteins.
8. The body wall consists of 3 layers. Pinoderm on the outside, mesenchyme in the middle and choanoderm on the inside.
9. The matrix in the middle of the body wall contains a gelatinous protein called mesohyl. This matrix contains amoebocytes and skeletal material.
9. Food, oxygen, and sperm enter the ostia through water currents.
10. They are bisexual and reproduce both sexually and asexually. Asexual reproduction occurs by buds or gameules.
11. The life cycle consists of amphiblastula or parenchymula larvae.