Symbion pandora (left) is a tiny animal that lives on the mouth whiskers of lobsters. Smaller than a grain of salt, it devours leftover crumbs from its host’s meal. Pandora lives on only the Norway lobster (right). At least two other Symbion species reside on other lobsters.
From left: Reinhardt Møbjerg Kristensen; Hans Hillewaert/Wikimedia Commons (CC BY-SA 4.0)