The Mudsters
The Mudsters are made up of soil and silt which is all washed about by the rain. Being friendly creatures, they don't have a lot choice about where they end up, and are not happy about the bother they sometimes cause.
Mudsters can be quite clever when they are able to use light rain to reform their shape and this is the way in which they shaped themselves into a little house for Noggin after he rescued them from the Long Itchington pond.
Like sand sculptures, mudsters can take any shape and if kept dry, can maintain it until the next rains come.