Botrylloides leachi is a colonial sea squirt forming flat, gelatinous sheets. The colonies can vary greatly in colour and can be grey, orange, yellow or red brown. The zooids are arranged in 2 parallel chains. Individual zooids are twice as long as wide and are between 1.5 - 3 mm longThe linear arrangement of zooids in Botrylloides leachi distinguishes it from the star like arrangement of zooids in Botryllus schlosseri. Botrylloides leachi is the preferred food of cowries, Trivia arctica and Trivia monacha.