Tera Mutant (Lower Body) (also known as Terra Mutant (Lower Body) in the SNES/PS version) is a boss that appears in Chrono Trigger, in the Black Omen. It is the lower half of Terra Mutant (Upper Body). The Upper Body absorbs HP from the Lower Body, and the Lower Body will be destroyed if the Upper Body is destroyed. The Lower Body itself is nearly invulnerable, taking little damage from physical attacks, and counters them with Life Shaver. It absorbs all magical attacks. The only reason to target the lower body is to Charm it with Ayla.
In the SNES version, the name of the monster was "TerraMutant"; Terra being the Latin word for the planet Earth. However, the name translates from the original Japanese to "Tera Mutant", and is named as such in the more accurate DS script. Tera is a prefix used in the metric system which denotes 1012, or 1,000,000,000,000 (one trillion). Appropriately, this enemy is fought after the Giga Mutant is destroyed (giga, meaning 109, or one billion, comes before tera).