it is normally recumbent, lying on its right side, roughly oval in shape, but fitting its body to the contours of its surroundings. the inhalent siphon is at the tip of the body and the exhalent siphon a third of the way down the right side. the siphons cannot be retracted. although the tunic may be clean, it is sometimes covered by a biotic film or overgrown by others of its species or other tunicates. the hind gut can be seen through the tunic and forms a simple curve, and this helps distinguish it in european waters from the fairly similar sea grapes ("molgula" spp), which have an "s"-shaped gut.