Sony's Rolly "music entertainment player", a palm-sized, egg-shaped device that rolls and spins like it's dancing to the music, is now available at Sony Style retail stores in the States.

Combining Sony portable audio technology and artificial intelligence, the company says the device offers "a unique combination of music, motion and fun."

The Rolly features 180-degree, horizontally opposed stereo speakers with neodymium magnets plus a digital amp but its real USP is not in the sound quality, but the movement that goes along with it.

Thanks to the built-in robotic technologies, the device is designed to move its "arms", "shoulders" and wheels - with six moving parts in total - to the beat of the music and there's around 700 hues of flashing lights too.

In the US, Sony is shipping the Rolly complete with choreography for three songs: "Also Sprach Zarathustra" (the theme from "2001 - A Space Odyssey"), Avril Lavigne's "Girlfriend" and Earth Wind and Fire's "Boogie Wonderland" but users can also create their own choreography thanks to the included software.

The Rolly, available in white or black with a 2GB flash memory, is on sale now for $400.