This was kind of strange
Solis Obscurus ….
The Obscurus could be largely invisible or appear as a flying, incorporeal, and amorphous entity with the appearance of a black, fluid-like cloud, or a violent torrent of darkness…
Some described it as a "dark wind" or "dark mass" with "shining white eyes". Its appearance could be oleaginous, or "rich in, covered with, or producing oil; oily or greasy". There had also been instances when a face briefly emerged from the shadowy entity, or a white glowing image of the host appeared inside of it.
Source: https://harrypotter.fandom.com/wiki/Obscurus
