What is this? Should I be worried?

[SteveCGY]

Just noticed this sprouted on a piece of rubble in my display out of no where. Just wondering what it is and if it's good or bad. Tried my best getting a picture.

http://i35.photobucket.com/albums/d194/Stevecgy/ADA87555-E19B-400F-B92A-BC7C23A0B888_zpscni5wi6h.jpg (http://s35.photobucket.com/user/Stevecgy/media/ADA87555-E19B-400F-B92A-BC7C23A0B888_zpscni5wi6h.jpg.html)
http://i35.photobucket.com/albums/d194/Stevecgy/912D777C-19CA-4CA6-9D89-CBCED7E11F94_zpsim8h4f74.jpg (http://s35.photobucket.com/user/Stevecgy/media/912D777C-19CA-4CA6-9D89-CBCED7E11F94_zpsim8h4f74.jpg.html)
http://i35.photobucket.com/albums/d194/Stevecgy/21A591B6-7AE3-412F-9776-E2C5507D1399_zps8fgl3cy5.jpg (http://s35.photobucket.com/user/Stevecgy/media/21A591B6-7AE3-412F-9776-E2C5507D1399_zps8fgl3cy5.jpg.html)
http://i35.photobucket.com/albums/d194/Stevecgy/E4040B72-BF9E-4895-9612-A03B38C478CE_zps48nzccu6.jpg (http://s35.photobucket.com/user/Stevecgy/media/E4040B72-BF9E-4895-9612-A03B38C478CE_zps48nzccu6.jpg.html)
http://i35.photobucket.com/albums/d194/Stevecgy/769780EB-3215-4AB3-AF8C-63F236D9465C_zpsnzctjljg.jpg (http://s35.photobucket.com/user/Stevecgy/media/769780EB-3215-4AB3-AF8C-63F236D9465C_zpsnzctjljg.jpg.html)

[denny_C]

ball anemone( actually a mushroom) they are fairly harmless( that species anyways) but do pack a powerful sting , they are completely nocturnal and often done hang around the light unless they are in the path of food:)

[denny_C]

could also be a strawberry but it doesnt quite look like it:)

[SteveCGY]

So it's safe to keep and see what it does? It seems happiest under my bubble coral so it has like an umbrella over it.