Sea apples, or sea cucumbers, belong to the Echinodermata group, along with sea urchins and sea stars.
They have five rows of ambulacral feet, like tentacles ending with a sucker, that they use to move around. The Australian sea apple is known for sporting three different colours: purple, red and white. Its skeleton is made of a scattering of small, hard needles covered with an external integument similar to leather.
The mouth at one end of its body is surrounded by 10 branching tentacles with taste and smell receptors. The sea apple exposes them to the current to filter the water and catch floating prey. It then puts its tentacles one after the other into its mouth.