Creatures down there have been separated from life up here for ever, we need to get the DNA sequenced for some of them, we may find some shocking discoveries of our ancestors 500 million years ago. Are there plans to bring back animal samples?
Still, you've got me thinking about this question. I would think the present-day fish that most resembles our ancestor of that time ought to be something less exotic. Perhaps something like a hagfish.
It is one of the reasons as to why giant squids are so mysterious.
So a definitely maybe :)