[Tuscaloosa Goldfinch]

Pickling lime:

https://www.askaprepper.com/how-to-preserve-eggs-with-lime-water/
A few paragraphs down in the article. Also there are YouTube videos:
Also called “waterglassing eggs”

[Squidpup]

[Cletus.D.Yokel]

Thanks.
That’s what I thought but wanted clarification.
The citric acid in a lime (fruit) would etch away the eggshell.
Slaked lime is a base and so would fortify/seal the eggshell.