The arshen is a large slug-like creature which dwells in subterranean pits. They exude a thick pitch-like substance which the Martian Tribes use to waterproof clothing, boats, and wings. The skin of a slain arshen is difficult to remove, but is semi-translucent and naturally waterproof. It is used for tent, tarpaulin, clothing and for covering the gejassoas frames that form the wings that so many tribes use for travel. The arshen seem ponderous and placid, but they have an unpredictable temperament that makes them dangerous. They can move more quickly than most imagine and they are capable of swallowing large animals or humans whole, and their corrosive gastric juices quickly break down their meals.