We've been wondering for two months when we would find out the true identity of the 'Mystery Oreo' cookie flavor. Tuesday was the day.

Oreo made the announcement on Facebook: It was a mystery for the ages. That is, the stone ages. The Mystery OREO cookie flavor is FRUITY PEBBLES TM cereal.

After debuting the Mystery flavor in October, Oreo also launched a sweepstakes encouraging fans to submit their own guesses online or via text message, with a $50,000 grand prize at stake. The contest ended on Nov. 30 but a winner has not been announced.

Many of you guessed Fruity Pebbles correctly on the spot. Others suggestions on social media included Fruit Loops, lemonade, and Fruit Stripe gum.