I remember seeing a toy once that was big and purple and had 4 arms.

Does anyone else remember that?

Was that ever in a comic book somewhere?

According to wikipedia, he was only in the toy line, not featured in the comics. He was named Riot: http://en.wikipedia.org/wiki/Symbiote_(comics)#Minor_symbiote

In Carnage USA, some of these symbiotes make a re-appearance as bio-weapons for the military.

I don't recall Riot having 4 arms.But yes there was a purple symbiote.

Only a toy?

That's too bad.

Marvel should create a new symbiote with 4 arms. It always looked really cool.

Since the Symbiotes change based on who is bonded to it, its possible for a Symbiote to give its host 4 arms. The problem with that is since there are so many Symbiote characters in the Marvel Universe that he might not make that many appearances, and might not be popular enough to continue his character.