The characters are wasps from the devastated nest of Ys’drktha. The other survivors from the cataclysm are being held and tortured in the pits of the neighbouring Ak’thaan nest, being slowly dismembered and eaten by drone wasps or fed to the writhing masses of larvae.
If thrown into a moat or a ditch, they react with water to make an area of ground a foot wide and solid enough to walk on rise from the bottom. If eaten-well, the body of the one who ate one of them is a real mess. Used to storm moats and forge rivers, streams and ditches. Must be kept dry until used.