The Phaistos Disk
Discovered in Crete in a Minoan palace in 1908, the Phaistos Disc has been a hot topic for debate among scholars around the globe. A circular object made out of clay, the disc is adorned with 241 different symbols that were pressed into it.
However, the symbols are not related to any other written language during that time or previously, so their meanings are unknown. The artifact is assumed to have been made between 1850 and 1600 B.C., placing it in the late Minoan Bronze Age.