The only name worse than "chain" for a social network feature would be "shackle". Both evoke the notion of slavery. You definitely don't want that.

But who am I to say anything, right? We have things that are reminiscent of "open your eye":

https://imgur.com/a/r0MtyVN

And we also have "linkedin" which is pretty much the chain idea.

So I guess anything goes nowadays.

I guess that's called challenge in most social media platforms?