This purple fabric knot is part of Donatello's bandana that was worn by Leif Tilden in Teenage Mutant Ninja Turtles II: The Secret of the Ooze (1991). The knot was salvaged by one of the Turtle dressers after filming wrapped. The eye mask part would have been glued onto the foam latex head. (That's a fact, Jack!)
According to The Sunday Mail, an Australian tabloid owned by News Corp, Donatello's voice changed in the sequel due to Corey Feldman's drug conviction. He was replaced by Adam Carl.
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