They are walking fungal creatures whose secretions rot the foundations of houses. They look like green fungus with eyes when at rest, and have a lot of spindly legs for scuttling away on.

They are found worldwide and usually live with your floorboards and skirting boards. They feed on dirt and smell of decay but their diluted secretions can be usefull by being made into cleaning fluid.

They can be gotten rid of easily with a Scouring Charm, unless you have let them go to long and they have grown too large, and then I would suggest contacting the Department for the Regulation and Control of Magical Creatures.