Dedik8d1

There is a two part wire (or cable), one end of which connects to the "igniter" near the fuse box, under the hood. The other part of the wire (cable) snaps into a small round metal circle component, Approximately about 2.5 inches in diameter or so.
What is that small round metal circle exactly, and what does it do.?The cable for that component was not plugged in on my car for the longest time. It was just hanging there loose.
I just noticed it today and plugged it into the round circle component.

Nothing has blown up yet, so I am taking that as a positive sign. Please advise! Thanks!