regular octahedron (noun)

1. In the anime series, the protagonist discovers a magical regular octahedron that grants special powers to its owner.

2. The fashion designer showcased a stunning necklace inspired by the shape of a regular octahedron.

3. The wizard used a regular octahedron as a magical artifact to unlock the hidden treasure in the fantasy novel.

4. The protagonist stumbled upon a regular octahedron while reading a mystery novel, leading them on an unexpected adventure.