The Sentry (also known as Blue Shield in the SNES/PS version) is an enemy in Chrono Trigger that appears in the Prison Towers in Present. During Crono's escape from his prison cell, he encounters pairs of Sentries in the center of four-way stairwells. Facing toward the southern wall of the room, these creatures block their sensitive black, spheroid bodies with heavy gray shields. Imprinted on these shields are the distorted, clownish faces. Attacking the Sentry while its shield is in place causes most attacks, Techs, or Magic to deal very low amounts of damage. Simply postpone attacking until the creature exposes it's round body and send a physical attack it's way. Sentry travel in pairs and will never been seen alone, unless its counterpart is destroyed by the player in battle. Rarely, Sentry attack Crono or Lucca by throwing tiny stones from behind their massive shields.