Like most Heartforgeians, nobody really knows what the Cthugha actually are. The most popular explanation is that they are a type of Boltzmann entity. However, even for Boltzmanns found in Vesania they are regarded as particularly peculiar.
Cthugha appear as a floating set of fractals that constantly changes. This is known to confuse and disorient observers. They are also able to incinerate solid objects.
Cthugha are hostile to all who enter their 'territory', disorienting intruders before incinerating them.
Cthugha appear to travel in factions, not bothering to communicate with other groups.