Apple of Discord.

 Apple of Discord is also known as Golden Apple of Discord (μῆλον τῆς Ἔριδος). It created a dispute between three goddesses.

Eris wasn't invited to the wedding of Peleus and Thetis. She became angry.

So, she decided to give them the Apple of Discord. Eris wanted to make the goddesses quarrel. 

Athena, Aphrodite, and Hera saw the Golden Apple of Discord. It was written "to the most beautiful" (τῇ καλλίστῃ). The goddesses began to argue about it.

Paris judged Athena, Aphrodite, and Hera. He gave the Apple of Discord. She helped him steal Helen of Troy. Later the Trojan War started.

This legend became famous in Ancient Greece. Also, the phrase "apple of discord" means that small quarrels can turn into big conflicts.