It's an encrusting algae that will adhere to your glass, live rock and equipment over time. Some people don't like, most love it. It'll help in reducing nitrates. It is also very natural looking in it's hues of pinks, purples and even greens. It is a hard algae and will need to be scraped from the front glass or any other areas you don't want it. It needs higher calcium levels to grow. Some people wonder why they don't have it in their newly set up tanks and then after time, it starts growing....and doesn't stop...lol. Sometimes it can take up to 6-8 months to really notice it growing. Keeping your Ca and Alk levels up with definitely help it along. As for Where it comes from? You need to already have spores of it in your tank for it to grow. If you don't have any spores, you can do everything there is to get it to grow and it won't. You normally get spores from live rock that you've put in your tank. If you don't have any, it's possible to get it from other reefers. Reefers are always needing to scrape it off their glass. It's not difficult to syphon the scrapings as they're removed. Then you can just put it in your tank and let it settle. You can also find pieces of live rock that have coraline growing on them. Putting these in your tank will seed it's growth.
As for it's benefits, I'm sure others that are much more knowing that I am will chime in soon.
