Crystal Heart

Crystal Hearts are objects found on any layer below the surface. When the player breaks a Crystal Heart using a Hammer, or explosives, it drops a Life Crystal which can be picked up. The life crystal can be used to increase your maximum health by 1 heart, or 20 health. It also heals you by the same amount. Crystal hearts cannot be used once the player has 400 health, which is the maximum obtainable legitimately. If you want to find crystal hearts very easily, then dig to the Cavern level since there is alot of naturally generated spaces or head to a corrupted chasm because if there is a path intersecting a few caverns; there is a good chance there will be a crystal heart, along with a lot of demon altars. Dungeons may contain crystal hearts too

While they can be hard to find, single-player mode worlds will actually contain dozens more Crystal Hearts than the player can use.

Multiple Crystal Hearts are usually found in the Dungeon and The Underworld.