Desbrachians

Desbrachians are large, insectlike creatures feautured in Metroid: Other M. They can be seen many times through the game but can't be engnged until the MB battle or until the Power Bomb is adquired, witch means they can't be fought normally until the game has been beaten. The first time they are fought, Samus has to beat some of them in first person, and then lock on to MB. Afterwards, they can be defeated normally, but can only be killed with a Lethal Strike. If let rest after they are downed, they will close their shells and begin to restore health. They guard some important areas of the Bottle Ship, witch can't be acessed until Samus returns to it.

Trivia
One can be seen hiding in its shell in the cutscene where Mellissa informs Samus of the situation in the Bottle Ship, but when the place is revisited with the Power Bombs, it is nowhere to be found.