Ortiguillas de mar

The snakelocks anemone is a sea anemone found in the eastern Atlantic Ocean and the Mediterranean Sea. The latter population is however sometimes considered a separate species, the Mediterranean Snakelocks anemone (A. sulcata). The tentacles are usually a deep green color with purple tips, the green color is often attributed to the presence of symbiotic algae within the tentacles but is the result of the presence of Green Fluorescent Protein which is present in corals, sea anemones, and some other cnidarians. The anemone tissue contains a symbiotic algae called zooxanthellae, which is necessary for the long-term survival of the sea anemone. When the numbers of algae diminish the anemone may appear dull grey. The algae need light to flourish, so snakelock anemones will be found in the sunniest pools. On average the snakelocks anemone is 8 cm wide.

Source: Wikipedia