“In the past, people have had some rather peculiar shellfish habits. The Romans apparently liked to eat clams that glowed in the dark. Pliny the Elder wrote about people’s mouths shining like fire, with bright juices dripping over their hands, down their tunics and onto the floor. Piles of empty mollusk shells have been found at the site of a Roman bathhouse in southern England, including bioluminescent angel wing clams (also known as piddocks). We’re these the leftovers from nighttime bathers, feasting on a twinkling midnight snack?”
Helen Scales, from Spirals in Time: The Secret Life and Curious Afterlife of Seashells