Among the different Discovery tokens, you may find a fish-bone symbol. Species with sych symbols on their tokens are considered to be Scavenger species.
Scavenger species (Sea Cucumber, Schooling Fish and Crustacean) are denoted by the icon next to the species name in the core species guide.
By itslef, this symbol has no meaning, but it can be referenced by other Discovery tokens, such as Whalefall from the Expedition 1.