Yup reef safe. Cool macro algae actually. Definitely not a red gorg, I hope this was just something extra. Plant them in the sand and watch the for a while and you can decide if you like them or not. If not in the display then if you have a fuge put them in there.
The Shaving Brush Plant is also known as the Painter's Brush Plant and grows in shallow water in the sand throughout the world. It has a central base with many long thin green leaves, which gives it the appearance of a shaving brush.
These plants help reduce excess nutrients such as nitrates and phosphates in the aquarium. Most herbivorous fish and invertebrates will not normally consume this plant, but sea urchins may uproot and consume this species. Plant the Shaving Brush in the substrate in a well-illuminated place in the aquarium or refugium. This plant will benefit from the regular addition of an iron supplement, as well as trace elements.