(Mmm, right click, add, set as background...)

"The  genus Tubipora has four nominal species;  though, according  to Veron,  these all probably represent only one valid  species,  T. musica.  Organ  pipe  coral is also a  massive  colonial  animal, readily  recognized  by  its blood-red  cemented  parallel  tubes interconnected  by  horizontal  platforms. As  per  the  Subclass bearing,  Tubipora  polyps have eight  tentacles,  arrayed  like feathery palms when exposed. Organ  pipe  "coral" is used extensively in jewelry  and  as ornament, and I can testify, is very often overlooked  underwater for being what it is. Raja Ampat.