No one supposed that dinoflagellates might actively kill fish as an evolved response for their own specific advantage, including a potential nutritional benefit for the algal cells. And yet the dinoflagellates do seem to be killing and eating fishes in a manner suggesting active evolution for this most peculiar reversal.

"Reversing Established Orders", p. 400 - Leonardo's Mountain of Clams and the Diet of Worms (1998)