Twenty-nine kilometres along Shark Bay Rd from the Overlander Roadhouse is the turn-off for Hamelin Pool, a marine reserve with the world's best-known colony of stromatolites. These coral-like formations consist of cyanobacteria almost identical to organisms that existed 3.5 billion years ago; through their use of photosynthesis they are considered largely responsible for creating our current atmosphere, paving the way for more complex life.
There's an excellent boardwalk with information panels, best seen at low tide.
