Sansevieria Night Owl is a cultivar of Snake Plant, aka Mother-in-Law's Tongue, with shiny, dark green spear-shaped foliage that is surrounded by creamy-yellow variegation. Known as some of the toughest houseplants, they store carbon dioxide acquired at night to use during the day, then releasing oxygen at night, via photosynthesis, when their pores open. This helps it to maximize efficiency in cleansing the air, as found in a study conducted by NASA.