is pale brown in colour, but can also be yellowish, greenish, rose or purple. It has a stalked tree form with digitate branches, arising from a limited encrusting holdfast. It is usually about 30 cm tall and has a velvety surface. Branches are typically numerous, with a diameter of about 7 mm. The sponge has a robust consistency but is easily compressible and very flexible.Under sheltered conditions, branches are occasionally flattened, antler-shaped and less numerous. The shape and degree of branching is greatly affected by the strength of the counter flow, with the much branched form being found in strong currents.