Magma Block

Magma Blocks are light-emitting naturally occurring blocks found in the Nether that cause damage when stepped on. They also have an animated texture.

Attainability
Magma Blocks are found naturally in the Nether near lava lakes.

In Traps
Magma Blocks damage living entities standing on top of them. As such, they can be used as a trap to damage mobs or other players. On killing a player, the death message displayed in chat is 'Player discovered floor was lava'.

In Farms
Magma Blocks do not destroy items, so farms can be made to kill mobs without losing the items. This is especially useful for farming Enderman because they do not teleport away from magma blocks as of snapshot 16w20a.