Bedrock

Appearance
Bedrock has a texture of a black rock with multiple shades of grey and black and a few white streaks across it.

Description
Bedrock can only be found very deep in the ground, at y=4 and below. Due to the fact that it has an extremely high blast resistance, it is guaranteed that no amounts of TNT can break through it, as if one piece of TNT is set off adjacent to the block and does not destroy it, no other amounts of TNT connected to the adjacent piece of TNT will destroy the block, and so wasting an eternity trying to break it with even the hardest of tools is not recommended, due to the fact that it has a hardness of -1, which basically means that when a player hits it, it gains 0 damage, basically -1 hardness makes a block indestructable by anything legitimate except creative. Its extremely hard blast resistance also made it useful for another thing.

World generation.

Bedrock is nearly indestructible, that's why it forms the bottom most layer so that no entities will fall out of the world and into the Void. Gaps can be found in the bedrock layer but it is extremely rare and it is also ill advised to go find one unless you wish for a spot to throw away anything worthless in your inventory.