A biodegradable, clumpable cat litter made from corncob and biomass components. The animal litter is a mixture of low swellability particles and pellets or fragments thereof of high swellability material. The low swellability particles are formed of corncob grit. The particles and pellets, if present are coated with mineral oil to which is adhered to a clumping agent. The low swellability particles compose 70%-1000% and the remainder is a mixture is composed of the high swellability pellets or fragments thereof.