The animal is abundant in the Caribbean, where it is commonly found in reefs of open water areas.

Aplysina fistularis consists of one or more yellow tube-like structures that arise from a closed base and are sessile.

Unlike the related species Aplysina insularis, A. fistularis does not develop rope-like projections around its tubes, although it may show some branching tendrils.

Newly formed sponges require a hard surface to attach to and grow on.

If a reef is heavily disturbed, such as being covered by algae or sediment, A. fistularis may struggle to establish itself and grow.