External auditory exostoses (EAE) are dense bony growths protruding into the external auditory canal. These benign bony growths are often referred to as surfer’s ear due to observations of these growths in the ears of individuals exposed to a combination of cold water and air. 

Recently, Trinkaus et al (2019) assessed available Neandertal temporal bones for evidence of EAE and compared to western Eurasian late Middle and Late Pleistocene and Paleolithic human temporal bones. The results indicated that approximately 50 percent of the Neandertal temporal bones showed evidence of EAE compared to only 10-20 percent of the other Pleistocene and Paleolithic temporal bones. The authors suggested the EAE were evidence of frequent aquatic resource exploration by Neandertals. 

Reference
Trinkaus et al (2019). External auditory exostoses among western Eurasian late Middle and Late Pleistocene humans, PLOS ONE.