That's a good looking one. I had one of the dreaded green brittle stars about 16 years ago, the ones that are known to be fish eaters. This was before I knew much about them but by the time I found out they were fish eaters it was in a 65 gallon with a 5" Mombasa lion fish, a 4.5" maroon clown and a falco hawkfish. It was never able to get one of them. This star would have two of its legs laying 8" onto the sand and reach its remaining legs to the top of the 24" tank rim. Not sure if I have any pics of it or not but I've never seen another one as big.