Sonic didn't exactly look like a hedgehog, but many of his imitators adhered closer to the physical make-up of their associated animals. Yes, many did indeed go through the whole anthropomorphization process, where something is re-designed to bear an increased likeness to a human, but at least they looked something like a real animal. Aero the Acrobat was definitely a bat. Gex was undoubtedly a gecko. And Mr. Nutz was most certainly a squirrel.