“But Decebalus was not one to be cowed easily, and still showed his spirit by taunting the Romans. As Trajan reached the Iron Gates, Decebalus sent him a warning inscribed rather surprisingly, according to Dio Cassius, on ‘a large mushroom’. This was probably a mushroom-shaped dish used for ritual purposes, and sadly not the only instance in history of diplomatic correspondence by fungi. The inscription advised Trajan to turn back and ‘keep the peace’.22.”
