>>127858>>130800>>130866>>130140It's not a part of a manowar's body, that floaty bit is bluer than that and is an inflated sac rather than gelatinous flesh.
It's an incomplete/dismembered moon jellyfish (which are really common) or similar species (pic related.) Happens all the time either due to wave action, predators, people or boats. They're not dangerous, but can sting.