Google changed the logo on its home page on, replacing its celebrated emblem with mysterious clusters of colorful dancing balls.

Moving a cursor over the blue, green, red and yellow balls makes the figures fly around the screen and change their shape. The orbs then group together to form the "doodle," the company's logo.

The company declined to provide any explanation for the new logo. As a result, speculation has been rife around the Internet about what the doodle means.

A few blogs have noted that Google's 12th anniversary was on Tuesday. Others, meanwhile, said that the doodle might pertain to a press conference to be held at the company's headquarters on Wednesday. The event is said to be for an announcement regarding search.

The company, which is based at Mountain View, California, often changes the logo on its famously sparse home page in celebration of anniversaries or significant events. The search engine Web site also does this to pay tribute to statesmen, artists and scientists, statesmen.

Recently, the company marked the 30th anniversary of Pac-Man by putting up the classic arcade videogame in a playable doodle.