Hole in basement floor

I'm in the process of finishing my basement, and I've got a hole in the basement floor near the incoming water line that is covered with a metal plate. I finally opened the metal plate, and it appears to be a capped-off pipe with water around it. See attached pictures. Could anyone tell me what this is? I apologize if this is something that should be obvious, as my plumbing knowledge is very limited. Thanks in advance! Mike

City sewer?

If you are on sewer, I would say that's your back water valve.

I've never seen this, what state are you in? My first thought, before you opened the sheet metal cover, was this was your sump pump crock. But yes, it could also be as Matt30 says, basically a one way valve to prevent the city sewer (if ever overloaded) from "back washing" into your basement. It's nice, cost me $1,000.00 to put one in my line, plus the flood damage that triggered its necessity...and that was with me me doing all excavation and installation myself. Mine opens up for servicing, but mine is in the backyard.

Totally agree with matt its a backwater valve likely Normally closed and its probably for a bathroom group in the basement.

Thanks much for the feedback everyone. I live in Wisconsin and I am on city sewer, so it makes sense that it would be a backwater valve.

Do I need to be concerned about the fact that there's water around the valve, or is that normal?

It's not normal but I would check it out. It could be just ground water from under the slab

looks like an old safe. might be booty in that hole...er would that be a booty hole?