Spongocoel, literally 'sponge cavity'.

Sponges have no proper body cavity or coelom. However, in the everyday sense of the expression, there is a cavity inside sponges, which is called a spongocoel.

Sponges have a single body cavity known as the spongocoel . The spongocoel is critical to the food gathering strategy of sponges.

ostia -spongocoel-osculum

A spongocoel is the cavity inside a sponge, such as Grantia, that is lined with flagellated cells and stores the food (tiny particles and bacteria) the sponge receives from filter-feeding. Inside the spongocoel, food particles are trapped on a layer of mucilaginous material and transported into the sponge's cells for digestion.