Haliclona cinerea is a species of sponges in the family Chalinidae. They are omnivores. Individuals can grow to 200 mm. They have sexual reproduction.

A soft, fragile sponge with an even, greyish light-brown or purple-brown colouration. It has few key external identification features. The sponge varies in shape from thin encrusting patches to laterally spreading masses of interconnecting branches and finger-like protrusions with large terminal exhalent pores (the 'oscules').

Haliclona (Reniera) cinerea (Grant, 1826) is a very variable species, forming grey-brown or purple-brown encrusting sheets with rounded lobes to tall chimney-like growths with large terminal oscules. It is very soft and when torn has characteristic and diagnostic "slime strands".

Haliclona cinerea (Grant, 1826) Order : HAPLOSCLERIDA Family : Chalinidae Form: Varies from thinly encrusting patches to smoothly rounded lobes to tall, chimney-like growths with large terminal oscules or laterally spreading masses of anastomosing branches. The shape of this species is highly variable.