The Mushroom Compound Tunicate or also known as Distaplia occidentalis is distributed in the Northeast Pacific from Alaska to southern California. The species is common on intertidal rocks and in protected environments. It’s found from intertidal to 20m depths. The colonial tunicate forms colonies of multiple club- or mushroom-shaped masses or stalked mounds. Its colour is variable from pale orange to purple, grey, yellow or cream. The zooids are circularly arranged or in an oval systems. They are colored white to pale grey. Each zooid has 4 rows of stigmata and the body is divided into two parts: thorax and abdomen.