Exploring the deep ocean floor: Hot springs and strange creatures. The ocean floor is home to many unique communities of plants and animals. Most of these marine ecosystems are near the water surface, such as the Great Barrier Reef, a 2,000-km-long coral formation off the northeastern coast of Australia.
Quick Answer. Egyptian pyramids often took 10 years or more to complete. According to the Greek historian Herodotus, the Great Pyramid at Giza was built in 20 years by 100,000 workers and was meant to be a tomb for Pharaoh Khufu.
The ancient Greek scholar Herodotus who lived around 450BC when the  Great Pyramid was already 2000 years old, was told that it took  100,000 slaves twenty years to build.  â¦  Most modern historians accept the twenty years but believe it was  more like 20,000 or 30,000.