Noko Bombette

A Nokobon Met is a small turtle with a bomb for a shell found in Super Mario Land 2: 6 Golden Coins. Mario must try to avoid them, though they mostly appear in tight corridors, making this a difficult task. It is one of the few enemies that cannot be defeated by a Fireball. Instead, they must be jumped upon. However, unless a Spin Jump is used, the attack will cause the Nokobon Met to explode a few seconds after the jump. If Mario is caught in the blast, he will take damage.

Trivia

 * They're associated with and probably related the similarly named and behaving Nokobons of Super Mario Land. The Nokobon Met exposition in the manual of the sequel, Super Mario Land 2: 6 Golden Coins even repeats Super Mario Land's "a turtle with a bomb on its back" description for Nokobon.
 * Nokobon Mets are also related to Buzzy Beetles, since they're both immune to fireballs, have a similar appearance and even share part of their Japanese name.