It is usually arborescent with a main trunk and a dichotomous branching habit of growth but can also be clavate, thickening upwards like a club.

The surface of the sponge is smooth and ranges in colour from white, cream or orange to light grey.

[2][3] Homaxinella balfourensis is found in the cold seas around Antarctica at depths down to about 500 metres (1,600 ft).

Water circulates through the sponge, entering through small openings, the ostia, and leaving through larger oscula.

Oxygen and food particles are removed from the water in the process and waste products are carried away.

These diatoms benefit from the protection the sponge provides which enhances their prospects for survival in the Antarctic winter.