Leathery sea squirt is an immigrant from Japan, which was brought to Europe via ships in the 1970s. It is a robust sea squirt which sits on a narrowed stem. The animals are usually brownish in color. The Leathery sea squirt is often found in harbours, on pontoons, on ropes and tires in harbours, and on stones lying under the low-tide mark. Leathery sea squirt is found in the Wadden Sea and in the delta region.