Oreocereus trollii
Native range: Southern Bolivia
Known names: Old Man Of The Andes Cactus
Hardiness: Can drop below freezing ( 0°F )
Mature Size: ~24" tall
Light: Full sun
Water: Allow soil to dry between watering, leave it dry for about a week before watering. 
Soil: Succulent mix, fast-draining
Dormancy Period: Winter
Pet-Safe: No
Plant Size: 2.5" pot
 
Messy hair day!
Spine and hairstyle might differ slightly from plant to plant due to the nature of seed grown plant BUT overall this cactus looks like it's covered with white cotton candy. Forms a creeping colony over time or isolate plant to grow as a single stemmed cactus.
There are sharp spines hidden behind the whispy hair so please be careful!