The Thing is Arnold's favourite soft toy.
The Thing is a medium-sized soft toy that looks like either a bear or a rabbit. It has been thrown off a air plane ride by Arnold, listened to Kipper introducing his own toys to Arnold, has been levitated by a anti-gravity beam, and has followed Arnold everywhere he goes.
Thing is either a bear or a rabbit. It is unknown if it is either both two or not, because its name was never mentioned by any of the characters at all.