(Following up on previous question about insulating a heated floor.)
Upon removing the carpet I found this weird thing in concrete, which rises up over fairly flat floor around it, making a very tiny cone-shaped "volcano". What may look like cracks are actually just lamp shadows from non-smooth ridges (there are 2 barely visible hairline cracks - see last photo, but they don't cause any concern):
Closer examination revealed a ½-¾" copper pipe wrapped in insulation tube (OD is just a tad under 1.5":
Behind the wall next to this UFO (Unknown Floor Object :) is the crawlspace under the stairs. I'm not sure, but if we have a sump-pump, it's located 5 feet away (in the direction perpendicular that wall; there is a hole cover ~1 ft in diameter in the crawlspace, but I don't remember seeing any power cords going in).
What is that pipe? Should it be sealed (and then - how)? I want to flatten that spot.
P.S. Townhouse, middle unit, built in 2011. Furnace is located on the 2nd level.