A recent article suggests that life exists in Enceladus' oceans:-
The trouble with the article is that it claims that life could exist in oceans with a PH value of 11 or 12. PH 12, as I recall from my school days, is the upper limit of alkalinity. So it seems unlikely that life could exist in such a high PH value ocean. Hmm, perhaps bacteria might survive, as extremophile bacteria have been shown to live in volcanic vents etc., but it does seem unlikely that multicellular life could exist in any ocean with a PH value higher than, say, 10. What is your opinion on this?
All speculative of course, but given the unlikely habitats that earthly life has managed to colonize and survive in, I am always hesitant to rule such possibilities out.
After all, we only know ONE kind of life (as found on Earth) and there are how many planets out there? If Earthly life was "seeded" from that evolved elsewhere, it may be like a cosmic pinball machine out there - with life evolving and scattering all over the cosmos. In my first course on Extraterrestrial Biology silicon-based life was seriously discussed (in contexts other than breast enhancement).
One thing is for sure - what we know is insignificant to what we do not know about the universe and life.