It's a calcerous green algae, genus Penicilius. It is resistant to grazing, and spreads by runners through the sand bed. It needs light spectra and intensity emulating a shallow lagoonal/grass flat environment. It needs a soft, sandy, substrate to grow in. IMO it probably has a better chance of survival in older DSB, 4" or more deep. It is not resistant to overgrowth by filamentous algae so it benefits from nutrient poor water conditions.
I keep mine under 250W 6500K in a 4" DSB. It is not the easiest algae to cultivate, but it is fairly durable. Associated plants would be sandbed-associated, like Udotea, Halimeda tuna, and seagrass. Plants like these are available from Caribean collectors, I recommend Florida Pets (online).
