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.
A project management group that studied the problem of building the Great Pyramid estimated that the project, using material and methods available at the time, might have required less than ten years to complete: Two or three years site preparation, five years of actual construction and two years to remove the ramps and put on the finishing touches.