| External membrane closely adherent to the sponge except immediately round the oscula. |
| The water from outside therefore flows in at the pores and finally makes its way out of the oscula. |
| In budding, aggregates of cells differentiate into small sponges that are released superficially or expelled through the oscula. |
| Water enters through pores called ostia, flows through canals to a spacious chamber called a spongocoel, and finally exits through large openings called oscula. |
| The basic body form of sponges consists of numerous small incurrent canals called ostia and one or more large excurrent opening called oscula. |
| Their oscula were not raised on conical eminences and were altogether most inconspicuous. |
