This limited edition cereal featured "fruity planets and stars and orange space dust that turns the milk green". The "space dust" came in a packet enclosed in the cereal and was intended to be sprinkled over the cereal and milk.
An article in the October 26, 1998 issue of Brandweek described Cosmic Crunch:
Quaker Oats is launching a limited-time extension of the brand called Cosmic Crunch that plays off a space theme with the fruit flavored corn and oat cereal pieces in the shape of moons, stars and planets, and packets of orange magic space dust that turns milk a sweet alien green...
...Packaging for Cosmic Crunch is flagged "Limited Time Only" and highlights the product's play appeal to its 6-to-12 demo with a back-panel cartoon storyline of what happens when a kid pours on dust and his milk and teeth turn green.
We're not sure if the misspelling of Cozmic Crunch in the Brandweek article was a mistake or if Quaker changed the name of the cereal between the the time of the article and the launch.
The cereal officially launched in January of 1999.