Also mistaken for fulgurite by the more naturalistically minded, apparently. Maybe most common in the Nordics, based on viking references?
Additional links:
https://www.nationalgeographic.com/science/article/100810-thor-thors-hammer-viking-graves-thunderstones-science
https://fi.wikipedia.org/wiki/Ukonvaaja [Finnish]
Not surprised, oral history…
Being able to write things down has to be one of the more important inventions.
I seriously suspect if dolphins and whales, ways of storing information they might be more intelligent than us.
Agreed fish and climbing trees and what not