Diagram of gemmules

An asexually produced mass of cells, which are capable of developing into a new organism or into an adult freshwater sponge is termed as a Gemmule. They are small bud like cells, which are formed by sponges to withstand unfavorable environmental conditions. A freshwater sponge reproduces both by sexually and asexually.

Gemmules are usually found in a round or a ball-like structure, along with a central mass of amoeboid cells and a thick peripheral layer of a small siliceous spicule.

The structure of Gemmules includes Micropyle, Spicule, Inner layer, Archaeocytes and an Outer pneumatic layer. The micropyle is an outer coat of a cell with a minute opening and the peripheral layer is made up of a thick pneumatic layer and air chambers, which helps gemmules to float in water bodies. The Archaeocytes are reproductive cells and the spicule is the sharp-pointed structure, which is involved in protecting the gemmules from <a href="https://byjus.com/biology/predator/">predators</a> and also provide structural support to the gemmules.