Diamont

The Diamont were a species of silicon-based rock-people who hailed from Mondreus. For some reason they have disappeared from the galaxy. They appear to be able to naturally transform into rocky spheres called Dialanches, which they use to bound around quickly as well as dangerously to their foes. While their diet is unknown, it can be easily presumed to be some form of mineral consumption due to their silicon-based physiology. With this in mind, it's extremely unlikely that they could consume living food to sustain themselves.

Spire is believed to be the last of their race.

Dialanche
Diamonts can and will transform into Dialanches when the need arises, which resemble large, rolling volcanic rocks. These alternate forms can attack by throwing out and rotating its sides around itself rapidly, revealing the spiky yellow core. As its design hints at, it maneuvers like a boulder; while at high speed its movements are a little bouncy and rough, it gains momentum quickly and handles with ease.

Dialanches can cling to walls, which it can then climb slowly. This climbing ability is not perfect, of course, in that it does have a tendency to fall off often (perhaps due to its own massive weight), and Dialanches will automatically detach from a wall when it chooses to attack an opponent, which is often used by Diamonts as an effective ambush tactic. Another setback to the Dialanche form is that it is incapable of climbing vertical surfaces, and a Diamont will not drop itself from the surface unless there is a platform or floor for it to safely land upon.

Notable Diamonts

 * Spire, last of the Diamonts

Trivia

 * The Diamonts were very likely named after diamontology and/or diamontologists, which your local jeweler likely is. This seems likely given their species' crystalline structures covering their body.
 * The Diamonts may also be a reference to a canceled Gamecube game called Raven Blade, which was being created by Retro Studios, but was stopped to free up resources for Metroid Prime instead. In Raven Blade existed a species quite similar to the Diamonts, although far larger and simpler in design, which could also toss lava projectiles.  Retro Studios ended up doing the designs of all the Bounty Hunters in the game Spire - the only known Diamont - appeared in, Metroid Prime: Hunters.
 * The idea that the Diamonts were created because of the loss of Raven Blade may be why Spire's race is said to have mysteriously disappeared, as another reference to their lost game.