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yup...but not AN ecology...many, many,many separate ecologies that have never interacted with each other or the surface.

There could be a cure for cancer down there or a plague that wipes us out ;)

not likely...it's been isolated from us for hundreds of millions of years..

What do you mean? The cancer part or the bio danger part?

yes

those ecologies are rilly rilly ALIEN.
some of those critters that live there
don't even use hemoglobin for blood.

their blood is not red...it's blue.

That is interesting, and I know its the case. But I still wouldn't trust it or potential alien bio-matter, to not cause harm.

it IS alien...for all intents and purposes it might as well have come from the seas of Titan.