Remember Knut? That fluffy white polar bear that stole the hearts of people worldwide, when he was abandoned by his mother in December 2006? We are sad to report that he is no more. Berlin Zoo officials announced that the four-year old was alone in his den on Saturday afternoon, when he simply collapsed and passed away. A postmortem to determine the cause of his death, will be conducted on Monday.

Knut's short life was quite eventful. Four days after birth, his also abandoned twin brother passed away, but the resilient Knut, continued on. After spending the first 44 days in an incubator, he was handed over to Thomas Dorflein, who became the bear's constant companion.

His heart wrenching story and the fact that he was the Zoo's first Polar Bear baby to survive, struck a cord in people's hearts, resulting in what became a 'Knutmania' in his home country of Germany.

The number of visitors to the Berlin Zoo doubled overnight and the Zoo's gift store was flooded with Knut merchandise, that ranged from key chains to postcards to stuffed Knuts. Germany's post office even featured the polar bear on its stamps.

His daily interaction with his keeper was documented in a blog that was avidly followed by fans from all over the world and his story, turned into a best-selling children's book. Knut even made the cover of Vanity Fair magazine where he posed alongside Inception star Leonardo Di Caprio.

However, just as things were going well in Knut-land, tragedy struck again. In 2008, just before he turned two, his keeper suddenly died of a heart attack. Almost overnight, Zoo officials noticed a change in the bear's behavior - From calm and friendly to uncharacteristically aggressive - Something they attributed to depression, caused by the loss of his best friend and companion.

Over the years, even as he grew from a cute cuddly baby into a rather gnarly adult, Knut remained the Zoo's star attraction - almost as popular as he had been, the first time he was spotted by the public, in December 2006.

While he will be sorely missed, the people of Germany have found a new four-legged creature to fawn over - This time it's not a cuddly baby bear, but Heidi, a middle-aged, cross-eyed opossum, which resides at Germany's, Leipzig Zoo. The gray-haired marsupial has over 110,000 fans of Facebook, is the inspiration behind a popular song on YouTube and even has a plush line of toys - And this, is all before her public debut, which is not expected to be until July 2011!

Resources: Dailymail.co.uk, Montrealgazette.com