The shell of the great ramshorn, a species of large air-breathing freshwater snail, is shaped like a flat coil, reaching 25 to 32 centimetres in diameter. It is olive brown to brown in colour. The snail has a pair of long, filamentary tentacles, with eye spots at their base.
The great ramshorn lives in still or slow-moving water with ample vegetation and is common throughout Europe and East Asia.
These snails feed mainly on algae, detritus and silt. They can carry various dangerous parasites that affect fish and warm-blooded animals.