The amoeba is a very well-known single-cell organism, but now here is something even more interesting, a unicellular organism visible to the naked eye! Part of a series of amazing new discoveries about deep-sea life:
A single-cell creature big enough to see, in the Nazare Canyon off Portugal. The fragile new species was found 14,000 feet deep. It is enclosed within a plate-like shell, four-tenths of an inch in diameter, composed of mineral grains.