Dr. Fritz and her colleagues started by assembling a three-dimensional digital model of the conch. They immediately noticed that some parts of its shell looked peculiar. For starters, a portion of its outer lip had been chipped away. That left behind a smooth edge, quite unlike Charonia lampas, said Gilles Tosello, a prehistorian and visual artist also at the University of Toulouse. “Normally, they’re very irregular.” The apex of the conch was also broken off, the team found. That’s the most robust part of the shell, and it’s unlikely that such a fracture would have occurred naturally. Indeed, further analysis showed that the shell had been struck repeatedly — and precisely — near its apex. The researchers also noted a brown residue, perhaps remnants of clay or beeswax, around the broken apex.