Found this info out about them with the same ones in the photos posted and the same as I have in my tank, Hope it helps
Scientific Name: Parazoanthus gracilis
Classification: Soft Coral
Common Names: Yellow Polyps
Description:
Yellow polyps are very distinctive. They are obviously yellow in color and have long thin stalks up to 1.5" long and long tentacles compared to most other polyps. The polyps are individual and do not connected in any way.
Care:
Hardiness: Yellow polyps are very hardy. They do seem to be one of the tastier soft corals and if there is something in the tank that might munch on the occasional coral, yellow polyps are frequently the first ones eaten.
Lighting: Can withstand most reef lighting schemes, but seems to do best under at least moderate lighting..
Water Current: Yellow polyps prefer low to moderate water motion.
Temperature: 76º to 84º F.
Aggressiveness: Very low.
Feeding: Yellow polyps are photosynthetic and do fine with no feeding, but occasional feeding of small meaty foods like brine shrimp is beneficial.
Supplements: No special requirement are noted. Normal acceptable water parameters seem to suite it just fine.
Tank Positioning: No special requirements other than keeping them out of forceful water flow. These specimens are usually placed near the bottom of the tank.
Propagation:: Yellow polyps will naturally propagate in the reef tank and the colony will tend to grow in size. Super Glue Gell can also be used for manual Propagation. Using a razor knife or simular detach the polyp at the base. Using alittle Super Glue Gel reattach to selected rock or structure..
Average Cost $15 - $40 small-large. Varies in location