From RWP Wiki
Ice Eggs are weaponry items in the Banjo-Kazooie series.
Ice Eggs, as their name implies, are Eggs that are made of ice. They have the ability to freeze their target temporarily.
In the Games
In Banjo-Tooie, the ability to use this variety of egg is learned from Jamjars on the Isle o' Hags Cliff Top. They can be considered an opposing counterpart to the Fire Eggs. 50 Ice Eggs can be carried at any time (100 if they are upgraded by Cheato).
Ice Eggs can be very useful, as they can freeze baddies in their tracks. After being frozen, baddies are more easily defeated, as they shatter into pieces while attacked in that state. Ice Eggs can also be used to temporarily clear fire from a pathway. In fact, this is required in one area of Terrydactyland.
Ice Eggs are also particularly useful against the giant Inky squids in Jolly Roger's Lagoon. The Inkies block pathways in the level by swinging their tentacles around, and the easiest way to pass them unharmed is by freezing them with an Ice Egg.
Banjo-Kazooie: Grunty's Revenge