TESS discovers a planet the size of Mars but with the makeup of Mercury

The TESS mission has discovered an ultra-short-period planet (USP) that is also super light. The planet is named GJ 367 b, and it orbits its star in just eight hours. The planet is about the size of Mars, and half as massive as the Earth, making it one of the lightest planets discovered to date.

source https://www.sciencedaily.com/releases/2021/12/211202141430.htm