commensalism 

A symbiotic relationship between two organisms of different species in which one derives some benefit while the other is unaffected.

Barnacles attach themselves to the shells of crabs. The barnacles recieve a home and transportation.

commensalism by Diana Stephens February 14, 2005

Commensals 

They are unknown friends on social networking sites like Facebook, MySpace, Twitter, etc. These are the people who just adds anyone they see on social networking sites. They, most of the time, sneak into photos, videos, etc. for their amusement. They also steals pictures and posts them on forums so that they, with their fellow commensals, have something to laugh at or even jacked at.

Hey, Sarah. I see that you have a lot of friends on Facebook. So, how many of those are commensals? You know, adding someone you don't know is dangerous.

Commensals by Jake Burrows June 30, 2010

Commentalist 

A constant commentary of all things minor, unnecessary and irrelevant, derived from an obsessive need to comment on everything with no particular purpose or outcome.

“That’s a talking point”: said the Commentalist, after no particular topic of conversation.

Commentalist by RMB78 November 23, 2017