In the stairwell at the Frick Breuer

I cannot for the life of me figure out what this strange excrescence is. It looks something like a relief map of an ancient Mayan village (as I recall them from my undergraduate anthropology classes), or perhaps an elaborate nest for a fancy insect community. I’m not sure it’s original to the Breuer building, since I don’t remember it from the old Whitney Museum days, but it’s certainly been there through the Met Breuer and now Frick Breuer incarnations. I kind of like not knowing, but if any of you fanatical Googlers out there can find out what it is, do tell.