Grimer is composed primarily of putrid, hardened sludge and grime. It smells incredibly foul, and can influence the abandonment of entire cities due to its polluting nature－even weeds don't grow where a Grimer has appeared. Grimer thrives in filthy areas, such as factories, garbage dumps, sewers and polluted water systems. It enters sewers and other areas with great ease due to its rubbery, semi-viscous body; for example, it can enter barred-off areas by slipping between the narrow bars.