Excalbian

This species are non-humanoid, carbon-based life forms.

Native to the planet Excalbia, life on this world was once thought to be implausible.

History

In 2269, the USS Enterprise was sent to investigate Excalbia, but only found a poisonous atmosphere and molten lava surface. Sensor readings indicated the presence of artificial power generation, indicating the
presence of "a considerable civilization there."

Previously thought to be scientifically impossible, the carbon-based lifeforms registered on sensors as being "almost mineral" in makeup, and were described as "like living rock with heavy fore-claws".
The Excalibans initiated first contact with the Federation starship, scanning the ship with a deep probe technology, conjuring a representative in the form of historical politician Abraham Lincoln.

In their natural form, Excalbians appear as a simple rock formation that possess glowing eyes, a distinguishable head, and two arm-like appendages. Also in their natural form, Excalbians radiated extreme body heat.

During the interactions with the crew of the Enterprise, the Excalbians became intrigued by the Human notions of "good" and "evil". During this interaction, they were able to demonstrate the ability to disable the Enterprise, going so far as to breakdown the shielding between the ship's matter and antimatter.

Science Officer Spock observed that this species appeared to possess the "ability to control matter and to rearrange molecules in whatever fashion was desired", which allowed them to create other beings that registered on Starfleet sensors as humanoid. Able to use the subconscious of the beings around them, the created subject behaved like the person they were portraying.

By 2381, it was known that when sufficient friction is applied, Excalbian bones break down and became acidic.