It's, um... a rock. Limestone, specifically. We call it "The Dinosaur Bone", thanks to its striking similarity to a giant vertebra.
It's about knee-high, which is not terribly impressive when you consider that we're talking MY knees, but hey. It's a cool rock, and when your husband is a dynamiter by trade, you landscape with the coolest rocks you can drag home.
What's in your yard? Are you a rockhound, or a brickbabe?