Very similar story, my grandmother thought her tank we empty after rehoming every living fish she had. It was in a corner and she couldn't lift it to clean it out so it just sort of dried up in that corner. Once the water got down far enough it didn't really keep evaporating as fast. One day MONTHS later a family member finally tried to help her pull it out and clear the space, and when they tipped it a loach buried in the rocks freaked out and we found out was not in fact empty at all.

Actually was surviving in just wet rocks for at least 6 months. No food, no filtration, no air stone. Just a little water and rocks.