Zoro

From Wikitroid, the Metroid wiki

A Zoro, occasionally called Zero, is the larval form of a Ki-Hunter. They come in two colors, red and blue. The blue ones produce Red X when killed in Metroid Fusion. Zoros turn light beige or grey and stop moving when they start to cocoon. The cocoons are safe to jump on. The red form is found in both Super Metroid and Metroid Fusion, but the blue form is only found in Fusion.