Falling spike

Falling Spikes are spiked obstacles that fall from ceilings, and were introduced in Super Mario World (although the Icicle from Mario Bros. can be considered a precursor). They 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. They are darker in color than normal spikes.

In Super Mario Land, a lone Falling Spike appears in the Easton Kingdom, specifically 3-2. In comparison to other 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.

They also appeared in Super Mario Land 2: 6 Golden Coins in the Pumpkin Zone and Mario's Castle.

They reappeared in the Game Boy remake of Donkey Kong and Mario vs. Donkey Kong. This time they get stuck on the floor after they fall. Mario or Mini Mario can use its flat end as a platform. After a few seconds it will disappear and regenerate in its original location.

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.