These structures popped up overnight in an outdoor hallway of the bio sciences building.
They're chimneys of mud, made by soil termites. It's supposed to be a sign of rain, or of spring, or of bored termites (depending upon who you ask). Here's another view.
They're not very tall, maybe six or seven centimeters, but I was still impressed. The nearest exposed soil is a long way away, and I would not have expected that a wee beastie would be able to find a space in the seam between a concrete path and a wall. But nature will find a way, and it seems that the smaller the beastie, the greater the patience. (what's that, Opal?--Oh, Pomeranians excluded!) A close-up shows the construction of these termite towers of Babel--not baked brick, but little pellets of mud, chewed and regurgitated and cemented in place by termites.
I wasn't able to get a good picture of the builders. They would climb up only far enough to wave their antennae at me, then disappear before I could get a picture. I spent five minutes crouched awkwardly in a narrow hallway outside of a building full of scientists, and a half dozen people squeezed by me. Only one of these people (who I would hope are curious by profession) stopped even briefly to look at what I was doing. He got down to look at them too, and was delighted and impressed. I think that's the right response, and I dearly hope that my students would pass that test.