Fairy Washboard get their name from their small size and distinctive raised ridges. A type of Haworthia, these plants are in the succulent family and range from light green to deep, dark green (sometimes almost brown/black). 

Like most succulents, these dudes like bright, direct or indirect light and like the dry out completely before being watered. Be careful not to water their leaves directly. The easiest way to kill a succulent is overwatering.