This is a paid asset, but now you can download Blue Loot Box for FREE, but please remember this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
Detail this asset from Unity Store: Original Link
Blue Loot Box v1.0
Set of 101 hand drawn Blue Loot Box. All icons are of a high quality. A good choice for any game in the fantasy style.
– Each icon is 256×256 pixels size (PNG);
– 101 unique icons in total.