Cannons are a prevalent obstacle in Braid. They tend to shoot either Monstars, fireballs, or clouds. Cannons have a fuse at the back which fires the cannon at regular intervals. These intervals can vary between cannons, from 15 seconds to a fraction of a second.
Ammunition
Cannons that fire firefballs most of the time have no use and are pure obstacles. If Tim touches a fireball, he "dies" (see Time Manipulation).
There is a limit of obstacles created by one cannon that can have appearance on one level at the same time