From the Super Mario Wiki
Retrieved from "http://www.mariowiki.com/index.php?title=%2B_Clock&oldid=1979086"
Super Mario Bros. Special
The item first appears in Super Mario Bros. Special, simply called "Clock", where it adds 100 units to the timer.
Super Mario Galaxy 2
+ Clocks appear in Super Mario Galaxy 2, as a green clock with a knob on top, with the minute hand pointed at it. These appear in several Speedy Comet missions and add ten seconds to the player's time limit, which starts at either twenty or thirty seconds. The player must collect these in order to complete the level. They appear only in the Speedy Comet missions for Sky Station Galaxy, Bowser's Lava Lair, Bowser's Gravity Gauntlet, Bowser's Galaxy Generator, and Stone Cyclone Galaxy.
Super Mario 3D Land
+ Clocks reappear in Super Mario 3D Land with a similar purpose. They appear in two different colors: cyan and green. Cyan clocks refill 10 seconds of the time limit, while green clocks refill 100 seconds.
New Super Mario Bros. 2
Both green and cyan + Clocks also appear in the Coin Rush mode of New Super Mario Bros. 2. The cyan clocks still add 10 seconds, but the green clocks add only 50 seconds to the time limit when collected.
Super Mario 3D World
Green and cyan + Clocks both reappear in Super Mario 3D World, where they add the same number of seconds to the timer as in Super Mario 3D Land. They once again appear to be somewhat rare in the gameplay. Like in Super Mario 3D Land, the cyan clocks add ten seconds to the timer, while the green ones add 100.
Names in other languages