Ice Plains is a flat, snowy biome consisting of ice and snow. Passive Mobs never spawn here, like desert and mesa biomes. These biomes are sort of rare and are spotted when in an ocean by seeing ice.
Grass is also found with random spruce trees scattered around.
Ice Mountains is a mountainous biome which can reach up to similar levels to the Extreme Hills biome. More commonly found than other hills biomes.
Ice Plains Spikes is a rare biome found in Ice Plains biomes. This contains spikes made out of packed ice and snow blocks are commonly found.