I was down at the isola tiberina today so I went to check the remains of the sculpted galley which adorned the "prow" of the island a couple thousands years ago. It is widely cited by Morrison as a major source for building the Olympias. Unfortunately some IX cent. Pope built a palace on it.
However you can see clearly the side of a galley, with the wale and the curved hull below it
And the outrigger as well, adorned with an animal head and the symbol of Esculapius. Pity there is no ram anymore!