Well I don't think it is an animal because magical creatures aren't classed as animals they're classed as creatures. And that's what a pymgy puff is. Animals are only things that exist in the muggle world. (well of course they exist in the magical world too) such as cats, dogs, mice and horses etc. And things such as bowtruckles, grindylows and pmgy puffs only exist in the magical world so therefore they're not really animals. If you know what Im trying to get across.