Plastoid (Arrowverse)

Plastoids are a hostile species with elastic bodies from the universe of Earth-19, who invaded their universe's Earth.

Biology
Little is known of Plastoid biology, other than they had elastic bodies that enabled them to shapeshift and stretch out their limbs. Plastoids are presumably humanoid and externally Human-like, as a meta-Human with elastic powers was mistaken for one, but it is unknown if that is their true appearance, or the result of their shapeshifting.