Platforms in either blue or magenta that appear and disappear in a certain predictable pattern: all blue platforms of this type appear at once, then disappear just as the magenta ones appear, which then disappear to let the blue ones appear, and so on. These platforms can be found in all chapters, but only at the ends of B-Sides and in rooms of normal chapters that include B-Side Cassette Tapes, with these platforms not appearing at all in C-Sides. Names for this object include Alternating Platforms, Cassette Blocks, and Rhythm Blocks.
These platforms make a reappearance in Chapter 9, but now with marigold and green platforms along with the blue and magenta platforms. They can cycle between all 4 colours or only 3 colours; for a four colour cycle, it starts with blue, then with magenta, then with marigold, then with green before going back to blue again, while a 3 colour cycle is identical save for simply omitting the green platforms (i.e. blue, magenta, marigold, repeat).