Lava

Lava is found at the spawn area. They glow in bright red and emit fire particles. They will kill you rapidly if you jump onto them.

Trivia

 * You can actually stand on lava without getting killed if you stand absolutely still.
 * Lava does about 20 damage each time it hurts you.
 * Debris of players will not be melted even if they're on the lava.
 * Realistically, you will be melted rapidly if you stand next to lava, but in the game, you don't.