A really awesome French band called Magma that plays a weird, usually bass-heavy hybrid of progressive rock, neoclassical, and jazz fusion. Like if Carl Orff and John Coltrane dropped acid together and formed a rock band singing about a utopian future civilization. This symbol appears in some form on each of their album covers (that particular variation was made for me on one of those "Christmasize your avatar!" threads on the CRFH forum ages ago).