THE SCENE: Pliny the Elder, one of the most prolific recorders of natural phenomenon in the ancient world, describes a report of the characteristics of a Triton (in other words, a merman).
THE TEXT: Ambassadors from Olisipo, sent on a mission with this purpose in view, reported to the Emperor Tiberius that a Triton, whose appearance is well known, had been seen and heard playing on a shell in a certain cave.
I have illustrious knights as authority for the assertion that a Triton has been seen by them in the Gulf of Gades, perfect resembling a man in his physical appearance. They say that he climbs aboard ships during the night, and that the side of the ship on which he sits is weighted right down, and, if he should happen to stay there an unduly long time, the ship is submerged.
The bones of this monster were brought by Marcus Scaurus from Joppa in Judea during his aedilship and shown at Rome among the rest of the amazing items displayed. The monster was over 40 feet long, and the height of its ribs was greater than that of Indian elephants, while its spine was 1.5 feet thick.
– Natural History, Pliny the Elder, 1st Century AD