The Thing is, as the name suggests, not a breathing being, but a machine. It is a small black box, that can easily be carried around by a nome. The Thing has been called thing by the nomes of the Bromeliad series, because they simply forgot what this box was all about until they accidentally activated it, by putting it near a source of electricity.
When activated the Thing's smooth black surface developes a series of complex lights and identifies it's self as a highly developed computer (the Flight Recorder and Navigation Computer of the Starship Swan) with the ability to talk and listen to the nomes. It takes all requests very seriously and has absolutely no sense of humour (HA!).