Unknown drain

In my unfinished basement I have I rough in for my toilet and sink and about 5 feet away there's this black cover that's flush to the ground, I have no idea what it is, and it looks like you can't pop it off and it was meant not to be lifted, can someone tell me what it is?
I know it's not the clean out, that's in the cantina
House built in 2004

It might be a another clean out. You should be able to open it up and figure it out. Could it be for a tub or shower?