The Petralona skull, embedded In a cave wall for 300,000 Years, appears to be neither Homo sapiens nor Neanderthal. The remains were discovered in the 1960s within a limestone cave near Thessaloniki

https://www.iflscience.com/this-mysterious-skull-baffled-scientists-after-being-embedded-in-a-cave-wall-for-300000-years-82562