Bedrock

Bedrock is a rare block with a very high durability against TNT. Bedrock can be hit with 50 direct hits by TNT before breaking. TNT in water near bedrock does not count towards that number. The current durability of bedrock can be displayed by right clicking it with a potato, in any territory. Many vaults use bedrock instead of obsidian because of its strength, and due to its rarity bedrock vaults usually contain the rarest and highest-worth items.

Obtaining
Bedrock can be obtained through crates, kits, and combat level and achievement rewards. The higher tier crates and kits both give out more bedrock than their predecessors.

Trivia
In OP Craft 1.5 bedrock had a strength of 25.