The Bombardier Beetle is a very dangerous mob that spawns in the Underground Jungle. These mobs are notoriously known for being explosive.
The Bombardier Beetle has a short range explosion attack which activates on collision with a player. Additional to the explosion attack on players; any blocks that have a weak blast resistance can also be destroyed on collision. This does mean that a house made of these blocks will be vulnerable to destruction.
The Bombardier Beetle has now officially made a come-back as of the 0.3 release due to several people requesting it's return. :)