Lots of good guesses this week! As many of you realized, this is a huge tree root making the best of a small tree pit. But it’s not a Norway maple (sorry John) or a mulberry (sorry Robert), but a sweetgum (Liquidambar styraciflua) (congratulations Brian!). (You can see the little mace-like seed pods on the ground.) The root does resemble a bicep (“Treebeard’s elbow”) flexing to crack the concrete (aka Robert’s Concretious blandmulsia):
Though sweetgum can be nice urban trees, their roots are quite vigorous and can lift sidewalks several inches above grade as they increase in diameter:
Thanks for all the entries – our readers are smart and funny!