Life doesn't just reside here. The reef itself is built by one of its smallest tenants. 

 

For more than 15 years, marine scientist Dave Wachenfeld has been coming down here to study coral polyps. These tiny creatures are closely related to jellyfish, but much smaller. They don't have a bone in their body. 

 

Yet for half a billion years, they've been nature's greatest builders, architects of labyrinths of limestone. 

 

Wachenfeld: “When we look at the surface of these soft corals, we can see the hundreds of tiny polyps.” 

 

Every bit of this reef has had an odyssey to get here. The coral starts out life as larvae, floating free in the ocean. For each one, the chances of survival are slim.

 

They have to run the gauntlet of a million hungry mouths as they cross up to 1000 miles of open ocean. Fewer than one in 100,000 complete the journey.

 

And then they’re faced with a second hurdle--finding the perfect landing site. Falling on sand or a crowded outcrop is death. Those precious few that survive will start a colony. Once settled, the larvae begin to grow. Transforming into adults called polyps. They develop tentacles that can grab food from the water.