Falling spike

Falling spikes are spiked obstacles that fall from ceilings, and were introduced in Super Mario Land.

Super Mario Land
In Super Mario Land, a lone falling spike appears in the Easton Kingdom, specifically World 3-2. In comparison to later examples, this one moves rather slowly, and resembles a conjoined pair of stalactites. Many such stalactites appear on the ceiling of this stage, without falling. Even after this one falls, the stalactites appear to remain on the ceiling because its sprite is layered on top of the stalactites. In Expert Level, there are six in that level. Some of them are not layered on top of any stalactites so they leave gaps after falling.

Super Mario World
In Super Mario World, falling spikes are found only in castles and fortresses, and are typically grouped together with standard spikes. They are slightly off-color compared to normal spikes. Unlike Icicles, falling spikes will remain on the ceiling until Mario or Luigi approach one, which will trigger it into falling, similar to a Thwomp. Once it falls, a falling spike will continue to fall through the floor until it disappears. If the player goes out of range and back again, the falling spike will return.

Super Mario Land 2: 6 Golden Coins
Falling spikes also appear in Super Mario Land 2: 6 Golden Coins in the Pumpkin Zone's first and second levels. It behaves the same as in earlier games.

Super Mario Advance 4: Super Mario Bros. 3
Falling spikes also appear in Super Mario Advance 4: Super Mario Bros. 3, in the level Bowser's Last Stand. While they act as they did in Super Mario World, they look the same as normal spikes.

Yoshi's Story
In Yoshi's Story, falling spikes appear in the fight against Baby Bowser, where they only fall if hit by an egg or Bob-bomb. By doing so, they can be used to damage Baby Bowser while he is riding one of the ghosts. After falling, they grow back shortly afterward.

Mario vs. Donkey Kong
In Mario vs. Donkey Kong, falling spikes get stuck on the floor after they fall when approached and then drill into the floor and soon regenerate on the ceiling after a few seconds, acting like a faster version of the icicles from the Game Boy Donkey Kong. Mario and Mini-Mario can use it as a platform.