FIRE CRABS: 

XXX competent, wizards should cope

Recognized by their grey/greenish skin and bejeweled shell, they have six legs. They have strong ranged fire power, which they shoot from their rears. They are easy to take out but, they are an endangered species (living on a reserve in Fiji) purposely killing or harming one would end you up time in Azkaban since they are protected by the Ministry. They have a shell that is both desisted by muggles and the magical community. If needed to defend yourself from these creatures, use any water spell or the knock back jinx.