Euxinic conditions have nearly vanished from Earth's open-ocean environments, but a few small scale examples still exist today. Many of these locations share common biogeochemical characteristics. For example, low rates of overturning and vertical mixing of the total water column is common in euxinic bodies of water. Small surface area to depth ratios allow multiple stable layers to form while limiting wind-driven overturning and thermohaline circulation. Furthermore, restricted mixing enhances stratified layers of high nutrient density which are reinforced by biological recycling. Within the chemocline, highly specialized organisms such as green sulfur bacteria take advantage of the strong redox potential gradient and minimal sunlight.