I had a bad outbreak, that looks like it aptasia, AKA Glass same thing. It looks a little light but there are variations. Kill it!
They still are coming back & I read so much! I ordered Joes Juice, from JoesJuice.com, it is said to be the best. After my order he replied twice. They say this stuff kills them permanently. Kalk paste works but leaves chance for them coming back & they will. Copperban, peppermint shrimps are options but when they bite, some parts gets away to grow more elsewhere. I had a bad outbreak because I didn't know what it was but then it was popping up everywhere! UGGGGGG!