The 127,000-hectare (310,000-acre)[1] nature reserve boasts the most diverse and abundant examples of living marine stromatolites in the world, monuments to life on Earth over 3,500 million years BP.

[2] Hamelin Pool is the eastern major waters within Shark Bay, separated from the western area by the Peron Peninsula, with a smaller water body just adjacent to its northern border with Faure Island - L'Haridon Bight the juncture being defined by Petit Point.

[4] Other locations for stromatolites include an underwater site (6 metres (20 ft) deep) in the Caribbean, Persian Gulf, and in the Great Salt Lake of Utah.

[5][6] The stromatolites in Hamelin Pool were discovered by surveyors working for an oil exploration company in 1956 and were the first living examples of structures built by cyanobacteria.

[7] The cyanobacteria living in Hamelin Pool are direct descendants of the oldest form of photosynthetic life on earth.

The cyanobacteria live in communities on the sea bed at densities of 3 billion individuals per square metre.

There are three basic types of stromatolite, the sub-tidal (always under water) columns and the inter-tidal (exposed to air and sun during low tides) anvil or mushroom shapes depicted in most pictures.