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Warning! This page contains spoilers for The Tower of Nero.
An Amphisbaena (plural: amphisbaenae) is a snake with a head on each end of its body.
It is believed that the amphisbaena were born from the blood of Medusa's head while Perseus carried flying over the Libyan Desert. Cato's army encountered this creature along with other serpents on their march.
According to Pliny, wearing a live baby amphisbaena around your neck could assure you a safe pregnancy. Wearing its skin could make you attractive to potential partners.
An amphisbaena gets on an Amtrak in Washington, D.C. and stares at Apollo and Meg McCaffrey. When it is still on by the time they reach Philadelphia, the mortal god goes it investigate and it snatches his wrist and recites some of the prophecy he heard before leaving Camp Jupiter. It then snaps out of a trance, stating it should haw gotten off in Baltimore before being shot and killed by Luguselwa.
- It can shoot poison from its mouth.