In Greek mythology, the bull sent from the sea to King Minos was the Cretan Bull.
Poseidon sent the magnificent white bull to Minos as a sign that Minos had divine support in his claim to the throne of Crete. Minos was expected to sacrifice the animal to Poseidon, but he kept it alive and offered another bull instead.
The gods punished this decision by causing Minos’s wife, Pasiphae, to develop a desire for the bull. Their union produced the Minotaur. Daedalus later built the Labyrinth to contain the creature.
The Cretan Bull also appears in the labors of Heracles. Heracles captured it and brought it to Eurystheus, but it later escaped and caused trouble around Marathon. It is therefore different from the Marathonian Bull, which Theseus eventually captured or killed in later myth.