2010 LC200 random engine knock/click and rubber o ring in oil pan

[mgrim]

I get a random engine knock/click occasionally when sitting at idle. It goes away with higher rpm. I pulled the oil pan to inspect and found pieces of a rubber o-ring about 3/4”-1” in diameter and it appears to have a slot in it. See pic of o-ring pieces. Any ideas where this o-ring may have come from???