Sources : Turbot

Pliny the Elder [1st century CE] (Natural History, Book 9, 67): In a similar manner the skate [squatina] and the turbot [rhombus] while in hiding put out their fins and wave them about to look like worms, and so also do the fish called rays [raiae]. For the sting-ray acts as a freebooter, from its hiding place transfixing fish passing by with its sting, which is its weapon; there are proofs of this cunning, because these fish, though the slowest there are, are found with mullet, the swiftest of all fish, in their belly. - [Rackham translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.69): In a similar way, the rumbus preys upon fish. This fish is large and strong, but slow. It hides in the disturbed mud and moves its outstretched fins, and when it sees the fish approaching, it seizes them and devours them. The evidence of this skill is that, although it is the slowest of all fish, yet it is very often found to have the fastest fish, the mullet, in its belly. And this is what the Lord says in the Gospel, that the sons of darkness are wiser than the sons of light in their generations. - [Badke translation/paraphrase]