Another suspect tradition. Imprisoning an innocent creature in the foundation of a new building. I know that various versions of throwing a human sacrifice into a hole before you started constructing a dwelling over the top of them had historically been thought to be standard building practice, but I didn’t think that this scaled down version of it would still be practiced as recently as the late 1800’s.
Usually when a frog or similar creature is found encased in stone the speculation is as to how it got in there. People aren’t usually aware of its presence and curious as to whether it is still alive.
I know that frogs can hibernate for extended periods of time, but 31 years? If the frog was placed in the cornerstone you would expect that would mean there was some type of opening for air and possibly water to keep the frog going. Although the revival of the frog sounds like the behaviour of an animal that is emerging from a period of hibernation I am doubtful that the frog was really there all that time.
If you have any stories of extended hibernation that might show me how wrong I am, please let me know!