Dictionary of Ichthyology  

tide pool = an area in the littoral zone that retains sea water at a low tide because of a depression or arrangement of rocky substrate; a year-round habitat for certain fishes and a spawning site for others.

From Wikimedia Commons: http://ja.wikipedia.org/wiki/%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB:Tidepools_Small.jpg

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