Neochilenia jussieui
Native range: Chile
Known names: N/A
Hardiness: Can take down to 32°F if kept dry in winter.
Mature Size: Grows slowly to ~6" inches tall.
Light: Bright direct sun, Half day sun- avoid afternoon sun. 
Water: Water during summer (let soil dry out completely), keep pretty dry during winter.
Soil: Cactus/Succulent mix
Dormancy Period: Winter
Pet-Safe: No
Plant Size: Grown in 2" pot, shipped semi bare root
 
Black/dark purple cactus, black/maroon/grey spines!!! This one is for you, goth plant lovers!
Fairly easy to grow but will require some attention during mid summer to make sure that your plant doesn't get sunburnd. Other than that, grow it like your typical South American cactus...so no summer monsoon flushing, just water once in a while.