They have a coating on them from the chicken called the bloom that seals the pores in the shell.
They should be treated with mineral oil or use the water glass method though I know some old timers that don't. Just do a search on preserving fresh eggs. Use the water bowl test.
Thanks, very interesting.
“Just do a search on preserving fresh eggs.”
Sir Francis Chichester, when he did his round the world single-handed sail in Gypsy Moth IV took waxed eggs with him...just good ole paraffin wax.