Bill Blaster Turret

Bill Blaster Turrets are special Bill Blasters that appear in every game of the New Super Mario Bros. series. They are essentially multiple Bill Blasters stacked as a pillar, but their cannons periodically rotate and fire in a predictable manner. Unlike standard Bill Blasters, they will still fire if Mario, Luigi, Blue Toad, or Yellow Toad stands adjacent to one of the cannons. At minimum, they contain two active cannons. Each adjacent space is also aimed in the opposite direction.

New Super Mario Bros. Wii
In New Super Mario Bros. Wii, their appearance has been slightly updated. The arrows are now white instead of red and yellow, and the bolts are black instead of white.