Sea urchins are considered a culinary delicacy, but supply can't keep up with demand. Aizat Faiz/Flickr hide caption

itoggle caption Aizat Faiz/Flickr

Young oysters live on old oyster shells and slowly mature while forming a complete shell. Astrid Riecken/Washington Post/Getty Images hide caption

itoggle caption Astrid Riecken/Washington Post/Getty Images