Every other photo on this and 2 other rolls of Kodak Aerocolor IV are perfectly normal looking so I don't think it's from processing. It doesn't extend outside frame boundaries. Did the lens catch the light in an odd way? I'm not sure how it happened. Below is a comparison shot.
It looks a bit like a long large predator holding a pink balloon-like net in its front foot with which to catch birds. Fortunately in the second picture both birds have avoided the trap and the little eagles at home in the nest still have Daddy and Mummy to look after them
Well that's the end of the story and the bell is sounding, indicating end of school for Xmas, children, so I'll see you all next year for more stories