egg shells disolve?

I was just reading a book about the “Old West” and the late 1800s. They talked about some men at a “Fancy Saloon” eating pickled Quail Eggs. THey told that in the bottom of the jar there was a layer of white powder. this was said to be the disolved shells of the Quail Eggs and that the Brine/ Vinegar mix to the pickeling solution had disolved the shells.

Does/can this really happen? I have never pickled eggs in the shell, but remove them before placing them in the pickling solution. I use the Amish Style solution made with Beet juice and also pickle the beets at the same time, along with som sliced onion.