I remember reading a article that the Navy had picked up bizarre strange noises on their sonar sets.
I agree, there's probably life down there that we have never seen.
I mean there's a jelly fish called the immortal jelly fish that reverts back to its infant form after mating. The belief is that the first one of its species might still be alive.
http://www.telegraph.co.uk/earth/wil...the-world.html
Which makes it a threat, or delicious.