Castle Geyser features and Scanning Electron Microscope image of algal filament in a silica sheath
linkOn the left is Castle Geyser during an eruption with a pool from nearby Tortoise Shell Spring showing photosynthetic pigments at the bottom. The middle image is of a small pool in the Geyser Hill Group in the Upper Geyser Basin with an outflow channel full of yellow, green, orange, red, and brown pigmented phototrophic microbial mats.