Sony Corporation’s new rolling egg-shaped digital music player swivels, flaps its ends and flashes colorful lights in time to music.

The 40,000 yen (USD 354), 300 gram (11 ounce) Rolly, set to go on sale in Japan September 29, comes with stereo speakers, 1 Gigabyte of internal flash memory and a battery good for about five hours of music. Overseas sales are still undecided.

The smooth white gadget, small enough to sit on a palm, has sensors that recognise which way is up, allowing volume to be controlled by turning the player clockwise or counterclockwise, and tunes to be switched by pushing or pulling it on the floor.

The Rolly may be a fun way to impress guests at home. Sony used a dim Tokyo hotel for a demonstration on Monday to reporters to show how it turned and stopped like a dancing egg, flapping the lidlike parts on its ends as though it were blinking.

The Rolly also spun quickly in place until it became a blurry circle.

Packaged moves to tunes will be available as downloads from a Sony Web site. But people will also be able to use a special program on a personal computer that analyzes music to come up with simple choreography that appears to match the rhythm of the songs, Sony said.

The motion programmes are sent to the Rolly from the personal computer by Bluetooth. More ambitious people will be able to programme original dances for their Rolly.