In my opinion it's not an adult jellyfish of any kind. The problem with the jellyfish suggestion is that jellyfish are passive "drifters" so they
don't really need limbs to move around (although it helps to keep the upside up, and the bottom side at the bottom

)... They do however need their
tentacles to feed. (They feed on plankton that gets caught in their tentacles.) This blob has no (visible) way of feeding much less a clear digestive
track. (But then again the picture is not clear enough to see any such details.)
The closest jellyfish it resembles (IMO) is the
comb jellyfish
Beroe Ovata (Comb Jellyfish)...
Which leads me to believe that if this is not part of some animal, then it's an egg off some kind.
1. It could be a jellyfish in its early stages, but if this is the egg or even a jellyfish in Polyp or Planula stages, then this is going to be one
badass giant jellyfish!
JellyFish life cycle example
Jellyfish Life Cycle
2. Or it may be a fish egg of some kind. But then again, if that's the case... I do NOT want to see what the mommy fish looks like!!!
And that's exactly it. The fact that thing is so big! (I take it "50-70 cam in diameter" means centimetres?

) I hope they kept it and/or studied
it...?
A true mystery indeed...
Edit: broken link
[edit on 27-10-2006 by Gemwolf]