One of the most fascinating aspects of Mono Lake are the tufa towers. These rock formations are made of calcium carbonate (limestone), but they did not form from ancient, compacted seashells like other limestone. The towers grew under water before the lake level dropped when calcium in the underwater springs reacted with the carbonates (soda) in the lake water. These towers are often used as nesting areas for ospreys, swallows and other birds.
Mono Lake tufa information