Asteroidea merozoite

Asteroidea 472A is a compound which exist in a solid form under certain conditions, but will vaporise in an Earth-like environment. In its gaseous form it is highly-dangerous, capable of liquefying the human body almost instantly if inhaled. Even in a lower concentration it is still dangerous, and considered worse in this manner as infected humans are forced to die a painful death after several hours.

In 2557 researchers on the experienced a leak while experimenting with this compound. It quickly made its way into the ship's ventilation and successfully killed the entire crew.

Trivia
Asteroidea is the taxonomical name for the Starfish family.