Purple and Northern sea urchins (Kitamurasaki uni) are very similar, but Northern sea urchins (Murasaki uni) are a size larger than their Purple counterparts. Purple sea urchins are about 6cm in diameter and Northern sea urchins are around 10cm in diameter. Purple sea urchin habitats are generally found in warmer ocean areas such as Kyushu or China regions while the Northern sea urchins are found in colder waters around Hokkaido and Tohoku areas. The purple-colored sea urchins commonly found at markets are generally Northern sea urchins.
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Revision date: October 22, 2018