Coral forms off shore from volcanic islands in tropical latitudes, developing a barrier reef that's separated by a growing lagoon. But over time, while the surrounding ocean wears away the main body of the island, the coral ring remains.
Landsat 7 "sees" the Earth differently than a camera.
By detecting light in discretely separate ranges of color or more accurately,
electromagnetic bands the instrument can tailor images to highlight particular
features being studied by experts. The different shades in these images highlight
various features specific to each coral colony. Patches of bright red show places
where coral reefs are actively populated with living organisms.