Everything reminds me of something else.
The little body parts are no doubt from votives. We moderns continue the practice with little statues of the saints, for instance. Motorists often keep a small but stately St. Christopher on the dashboard of their cars....I thought bad drivers should have one where he's cringing and holding his hands & arms up to protect his face contorted in an expression of terror.
The Tiberina island that sits in the river in Rome between the Forum Boarium and Trastevere district is actually man made. It formed when silt built up after the king Tarquinius Superbus was deposed in 509BC. His wheat fields just across the river were devastated by the angry Romans and thrown into the river there. With low water levels, they collected silt over time....200 years later, with a plague threatening Rome, the Senate sent a delagation to Greece to get some medical advice. They brought back a snake thought to be the god Asclepius. The snake jumped ship in the river and settled itself on the Tiberina, thereafter a refuge for snakes and the sick....and it of course is a great place for quarantine separated from the general traffic of the city.