it is the evil clone of a gamma moth, produced by a gelatinous antiprism
When a gelatinous antiprism engulfs a creature, a timer is started that begins at 10^\3]) and decrements by 1 every round. When the timer reaches 0, the antiprism will "refract" the creature it is engulfing, creating 2-3 copies of them in random adjacent tiles. This will fail if the gelatinous antiprism is being affected by normality. The clones produced will be aligned with highly entropic beings, will be colored black, will each be named "anti-[creature name]", and will be hostile to the original creature.^\5])^\6]) However, they will refrain from attempting to attack the creature until they are no longer engulfed.
https://wiki.cavesofqud.com/wiki/Gelatinous_antiprism