For the exact same reason people post links to other things, it's interesting. It's always been more "hacker" than "news" here.
Incidentally, check out this wacky alien-looking worm that exhibits bioluminescence even though it lives its entire life inside of a tube, so there is no one to perceive it: https://en.wikipedia.org/wiki/Chaetopterus
That was neat, though it does mention there are some other creatures that can choose to share the tube and the research about it may be lacking in smaller companion life (bacteria or other lifeforms).
HN is not Reddit. We like comments that add information and dislike comments that only express brief reactions, jokes, etc. Keeps the signal to noise ratio high.
Incidentally, check out this wacky alien-looking worm that exhibits bioluminescence even though it lives its entire life inside of a tube, so there is no one to perceive it: https://en.wikipedia.org/wiki/Chaetopterus