This colonial species is found in both tropical and temperate waters worldwide, recorded in the Atlantic, Pacific and Indian Oceans in both the Northern and Southern Hemispheres. It encrusts jetty pylons and rocks, and is made up of meandering double rows of zooids with occasional common cloacal apertures in the colony. It is highly variable in colour, but often includes shades of red, white, orange and yellow. Some forms are almost identical to other Botrylloides species, such as B. niger and B. diegensis, and it is probable that many colonies of B. leachii observed in SA are actually one of these species. It is also similar to Botrylloides perspicuus and B. anceps, but can be distinguished from these species by their form, which is lobed or tubular for both species, with the zooids arranged in straight rows to a large terminal aperture in the case of B. anceps. Most washups of these similar species turn out to be B. perspicuus, due to its habit of attaching to sea grasses, although many are misidentified as B. leachii.
