Snowballs are a throwable projectile that deals 1 damage and can be used to craft a large snowball. They are only obtainable on Christmas Day.
On December 25th, snow falls in all outside environments and settles on the ground. Snowballs can be picked up by simply clicking on the snow and are thrown by clicking again.
Snow will melt when dropped outside of a snowy environment, but will not melt if left in the inventory.
Once a snowball is thrown, it remains in a thrown state, even if it has already landed. This means that if it eventually falls, it will still count as being thrown by you and can cause damage to enemies and, if you're unfriendly or dueling, other players. Snowballs won't cause damage if they're dropped from the inventory, only if they're thrown as a projectile.
Snowballs cannot be engraved. If you attempt to do so, Tavelor will tell you not to be ridiculous.