It's an ingredient for the "Ice Key" which opens the castle of Rem Boreas
To obtain this item follow the instructions:
- First you have to get the Iceberg Tip to get through the Ice Cavern on the North West of the kingdom.
- At the Ice Cavern you must get the Snow Grass along with the Mother's and Child's Tears.
- Then go to the Mother Stone where you got the Ice Star and melt the Ice blocks (The pink and the green one).
- On the 1F of the Family Rock/Mother Stone you will find the Ice Crusher. It's a bomb for the Ice block covering the entrance of the Underground Path at the South East of the kingdom on the Blizzard Lake.
- On the 2F you will find the Flower Petal.