Basement mat worth lifting to see whats lower than it? I've been contained by this house for about a year or...

I've been contained by this house for about a year or two immediately, and ever since i was contained by my room I put a dresser in the corner. However I lately moved it, and theres a hollow circle spot under the mat that sounds like wood over a hollowed nouns.

Now its a basement so it should be concrete, anyone know if its anything worth checking for? Or merely a drain or some sort of piece?

Thanks.
Answers:    My guess is that it is either an infirm sump pump that has a wood hatch or an older drain. I'm a curious sort however, and if it were me (and the house be an old one) would verbs up the carpet to see if it's an mature bootlegger's storage room or old escape tunnel :)
May at some point within time, when the carpet be laid, plywood over moisture barrier might hold been installed onto the concrete until that time the carpet be laid to help contained by the absorption of shock or shudder. Plus to aid in the longer duration of the mat. Carpet just laid on concrete will wear out faster due to the rubbing of the final membrane over a greater shorter time frame.