One of the most stunning and unusual earthbound features seen from space is not found in one stationary location. Large phytoplankton blooms, made up of an uncountable number of microscopic (single cell) organisms, can be seen by satellites orbiting the Earth. The plume-like swirls cover large swathes of the ocean, usually near the coastline. Phytoplankton thrive in warm temperatures, and the swirls often grow larger when they come in contact with nutrient-rich water from river deltas. Some calcium-rich phytoplankton swirls appear a milky white while others take on a red hue. They are an important source of nutrients for marine animals, including whales, but certain types (the so-called red tides) are toxic and can cause problems for animals and humans.