Same thing with the famous English moths. They were white, so that they could hide on the white bark of trees. Then industrial pollution turned the trees black, and the moths turned black. Then a century later, they cleaned up the pollution, and the bark went back to white, and so did the moths.

But in fact, the original (pre-pollution) population had something like 10% black moths. They were still there, despite a few million years of evolutionary pressure against their coloring. (Perhaps because burned trees would occur sometimes over the years.) When the trees turned black, the population shifted to 90% black moths. When the trees turned back to white, the population reverted back to 90% white moths. No evolution of a new feature, just a shift in the distribution of existing genes under changing selection pressure.