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.
It is believed that thousands of slaves were used to cut up the large blocks and then slowly move them up the pyramid on ramps. The pyramid would get slowly built, one block at a time. Scientists estimate it took at least 20,000 workers over 23 years to build the Great Pyramid of Giza.