If it is a jellyfish, it might be a Stygiomedusa Gigantea. This type of jellyfish – which can grow up to six metres in length – has only been spotted 114 times in 110 years, so details on it are scant.
But again, the appendages get in the way.
Another suggestion is Deepstaria Enigmatica, another rarely-studied jellyfish, which like most of its kind is colourless.
However it has reported to have a brown stomach, with one description saying the passages to the stomach are ‘somewhat irregular-edged, forming a reticulate network’.