Breaking P-Trap Cistern in Basement

Howdy,

My house has a 'rough in' for a 3rd bathroom in the basement. This 'rough in' consists of a cistern (into which I'll install a sewage pump), drain pipe for sink, connection for wax ring for the commode, and an enclosure for the P-trap for a tub.

The sink pipe is exposed, as is the connection for the commode. However, the P-trap for the tub is enclosed in something. It's like a plastic lid, but I can't remove it. I can pry it up a bit, but upon further inspection it looks like it's a mini-cistern. If it is a complete cistern, I don't want to pry too hard and break it; but I can't see any way to get the lid off. Does anyone have any ideas? A picture is attached...

Thanks!
-Josh

I believe that it is just a plastic bucket they put over the pipe to keep the cement from filling in....

Terminate with extreme predjudice!