Pendulum

Pendulums are uncommon hazards in the Mario series. They first appear in Super Mario 64 and Super Mario 64 DS as somewhat common obstacles throughout Tick Tock Clock. In Mario Kart 8 and Mario Kart 8 Deluxe, pendulums appear in the Tick-Tock Clock course as notable obstacles. In most cases, pendulums block or damage the player's character when touched.

Super Mario 64 / Super Mario 64 DS
In both Super Mario 64 and its remake, pendulums appear throughout Tick Tock Clock as part of the level's clock-based aesthetic. A small pendulum swings within the grandfather clock this level takes place in, likely the one encountered at the very bottom of the level. Certain other pendulums appear higher in the stage, often over pits, requiring Mario to time his jumps when encountered.

In The Pit and the Pendulums, two pendulums provide a decent challenge for Mario halfway up the clock, requiring him to cross past them and back without getting pushed off, which results in him dropping a good distance.

Notably, the pace at which the pendulums swing is dependent on the time the clock displays when Mario jumps through it. Depending on this, the pendulums may swing at a quick pace, or they may not swing at all. If this is the case, the pendulums are frozen in place, proving much less of a threat.

Mario Kart 8 / Mario Kart 8 Deluxe
In Mario Kart 8 and its port, larger pendulums appear as hazards throughout, though they are found far and few, swinging at a much slower rate.

Two of the pendulums swing right in front of ramps the racers are required to cross, although there are also Item Boxes over the ramp the racers may break through right before dodging the pendulum. If a racer collides with the pendulum, they are greatly slowed down, usually dropping down in front of the ramp.

Each pendulum displays the Lightning icon as well as the Mario Kart logo on its front and back. A pendulum is also shown on the course icon.

Super Mario Bros. Encyclopedia

 * "They swing back and forth inside the Tick Tock Clock."