Red Heart Cubes

Red Heart Cubes are obtained from the 3 most difficult puzzles in the game, and they do not appear in the inventory. They look like a red cube, with one corner missing, with a smaller yellow corner inside. The 3 of them fill an empty wireframe in a room called the Temple of Love, and resemble a red heart, and the logo of Kokoromi, an Indie development group which Phil Fish is a founding member of.

The red heart cubes can be found in the following rooms:
 * Black Monolith Room
 * Security Question Room
 * Telescope Room