All are entirely aquatic, lacking the broad belly-scales found in most other snakes and possessing dorsally located eyes. Their most notable feature is their skin and scales. The skin is loose and baggy, giving the impression of being several sizes too large for the snake, and the scales, rather than overlapping, are tiny pyramidal projections that lead to their common names. These snakes are ambush predators, lurking at the bottom of rivers, streams and estuaries, and waiting for fish to approach, which they grip with their coils. The rough scales allow them to hold the fish despite the mucus coating. Adults grow to between 60 cm and 2.43 m in length.