Stretch Shroom

Stretch Shrooms are a type of Mushroom Platform found in the New Super Mario Bros. sub-series. Their characteristic behavior is contracting and expanding at constant intervals, pulling anything and anyone on the ends of the platforms to the center when they contract.

New Super Mario Bros.
Stretch Shrooms first appear in New Super Mario Bros., where they are blue platforms. They appear only in World 5-A.

New Super Mario Bros. Wii
Stretch Shrooms return in New Super Mario Bros. Wii, behaving the same as in New Super Mario Bros., though they are now colored pink. They appear only in World 4-5.

New Super Mario Bros. 2
Stretch Shrooms reappear in New Super Mario Bros. 2, behaving identically to previous games. They appear in World 6-3 and the third level of the Gold Mushroom Pack.

New Super Mario Bros. U / New Super Mario Bros. U Deluxe
Stretch Shrooms appear yet again in New Super Mario Bros. U and its reissue. Their behavior is largely unchanged from their past appearances. They appear in the levels Dry Desert Mushrooms, Seesaw Shrooms, and, reprising the second aforementioned role in the challenge Rickety Sprint. Stretch Shrooms are among the very few objects that do not return in New Super Luigi U.