This is better than Oda’s explanation of it, honestly. Such a weird thing to have a character do.

^ lol

Now this is factual

It looks like he is wearing a long sleeve (Like Caribou) and his first elbow and where his arm ends.

I think he is a Long-Arm

Wait... this isn't a head cannon

THIS IS CANNON

Yeah hes definitely a Long-Arm that's why he has an extra joint

It says on his wiki page