Chernaya Past (black mouth) is a small spring on the Ustinova Slope of dwarf geysers, located several meters upstream from Moydodyr pulsating spring. Tiny cavern is light pink on the inside and framed around the edges by black thermophilic algae. Water is boiling and splashing inside.
The spring is clearly seen on a steep grassy slope. It does indeed look like an open mouth of some strange creature.