Major Terragen invertebrate phylum.
Nematodes are unsegmented pseudocoelomic (false body cavity) round worms with tapering ends. They inhabit virtually all habitats, both free living and parasitic. Usually microscopic, but the largest species may be up to 8 meters in length. There were believed to have been over 1,000,000 terragen species, although many were lost with the ecocide of the Industrial, Atomic, and Information ages (it is speculated GAIA may have either restored these or created new similar ones in their place).
Nematodes are widely used in biotech and for gengineering purposes; their small size and relatively simple organization makes them a very popular subject to work with. Almost every terragen habitat and biosphere hospitable to baseline and nearbaseline humans includes nematodes as an essential part of soil biota (often many millions ins a cubic meter of topsoil).