An interesting read about the Tumi.

“I was used to seeing the Tumi in all types of Peruvian handicrafts: wall ornaments, copper artefacts, wall hangings, carpets and jewellery. I knew the Tumi shape well, but It had never occurred to me to think that it was a knife, or what it was originally used for. It was only after reading my brother’s article that I came to realize that it was used to carry out trepanations (trephinations) on people’s heads!”