My youngest sister came to town to visit, from Utah for a week and it was really nice. She stayed with my other younger sister, and we had a group trip to Ohiopyle, where there’s a river, lots of woods and bridges to tromp around on, then a day later we visited the museum where she used to work, then the next day an amusement park.

At the museum they let me into the Paleolab where my sister has friends. One skeleton that was sitting around in pieces was an old mastodon, around 120 years old or so. Dan P. (the preparator) said they’d taken it down before it had a chance to fall down, so now they were cleaning and remounting it. He kept calling it “the elephant in the room.”

Underneath a table, on a cart, was a huge plaster lumpy thing — a “jacket” of plaster around a mass of earth containing fossils, which had been wrapped up at whatever dig site, but never had been opened. No one, including the preparator, knew what was in it. The museum is still full of old work that needs to be prepared and studied — Dan was working on specimens gathered in 1930 and something else from 1910; Mary Dawson, the curator emeritus who’s worked for the Carnegie at least 40 years, in her office was working on a bunch of specimens brought out of the Arctic in the 1960s — when she was personally on the trip. She’s a tiny little woman over 80 now, in a wonderful office filled with bones, maps, microscopes and zillions of little bitty glass vials with old typed labels.

She picked up a tiny open box like the kind you’d have a piece of jewelry in, with cotton under it, but in it were tiny black specks. Honestly, they looked like cockroach dirt. “Mice teeth,” she said.

“How do you know?!” I asked. My sister in the past has made proclamations similar to this, pointing to tiny, tiny bits in a matrix of smooth-edged gravel, saying confidently this or that was fish poop, or something else. Somehow, they recognize things.

She showed me the mice teeth under a microscope. They were black, but looked like human molars, with anatomy like you’d expect. They really were teeth.

Amazing. And later, when we were walking outside the Cathedral of Learning, my sister mentioned that the stone of the window ledges contained fossils. So we looked at them. The acid rain here, she said, has eaten away the stone enough to reveal a lot of the tiny fossils. And you can see little seashells and things in the stone. She said it’s Indiana limestone, which is typically full of fossils.

So I learned stuff, like I always do when this sister's around.