I don't know why I've gone from convincing myself of the plausibility of life starting in comets, to believing that super-intelligent amoeba shaped creatures reside in there surviving for millions of years, and can even control the comet like a spaceship, albeit needing solar flybies for thrust, and sequences of gravity assists to change their orbit. I have zippo evidence for any of it, except for the strange things that have been discovered about comets in the last 26 years, with the stardust sample return, Halley Comet flyby, and a couple of other NASA missions. Basically from the 1986 Halley flyby, a "dirty snowball" model was indicated and still mostly fits even the new evidence.
1) comets, although mostly water ice appear to be covered in a thin coating of very dark black carbon soot. Not predicted. Origin completely unknown.
2) Stardust samples from the corona included minerals that formed at extremely high temperatures, that were predicted not to be in comets, due to the mineral origin requiring 1000+ degrees C, and the Oort cloud never being subjected to anything like that.
3) DNA bases were also found in the stardust indicating that they were ejected from the comet.
4) Minerals were also found on one of the comets that indicated there must have been liquid water in the comet.
5) Gaps in the carbon soot layer, were evident when comet has a corona. Having a look at the picture they looked like bright circles in the dust layer with the ejecta shining through, on either side of the comet,.
6) Comet surface almost perfectly dry, yet not far under the surface is mostly water ice.
Anyway, there is more but it made my imagination go wild with possibilities.