Era worms or asymmetria are an old, very strange group of marine organisms that are related to the dibranchiates. Their most defining trait is the lack of any symmetry in their outer layer and the organs associated with it, which seem to grow at random in patches of varying size. This trait seems to be the reason they survived with this odd mutation, as they were able to develop larger gonads. The lack of symmetry left them with little choice in niches to inhabit, however. Era worms are found in several lagoons in tropical to temperate climate. Most of their lifetime is spent in an egg. Should the right conditions arise, all era worms will hatch at the same time and produce a poison that will kill everything in the lagoon. First they are filter feeders, then they will feed on the carrion and microorganisms that are adapted to era worm outbreaks, before they mate, release their eggs and die. Some species of marine tetragnathes are immune to the poison and get attracted to its smell, which they will follow to feed on the abundant era worms in their lagoon; especially notable are the erabanes, a group of beakfish which grows a special beak when exposed to the poison.