It is native to the western and central Indo-Pacific where it is usually found anchored to a hard surface in shallow water.

A colony of Atriolum robustum consists of a number of hollow, urn-shaped zooids up to 1.5 cm (0.6 in) long, each with a large circular terminal hole, the atrial siphon, and connected by an encrusting base.

The tunic (body wall) is firm to the touch and is perforated by a number of pore-like buccal siphons, each raised on a slight elevation, giving the zooid a pine cone-like appearance.

This sea squirt is sometimes confused with Didemnum molle but that species has a network of internal channels and exudes mucus, making it sticky to the touch.

Sexual reproduction involves sperm being drawn into the body cavity with the inflowing water current and eggs being fertilised internally.