Slime Crown

The Slime Crown is a boss-summoning item that appears as a small Blue Slime wearing a crown. It is used to instantaneously summon King Slime, in any location, who otherwise can spawn randomly at any time without the use of a summoning item (though only in the outer two thirds of the map, laterally).

Trivia

 * The Slime Crown's sprite seems to be a mashup of Gold and Platinum, the two types of crowns that can be used to craft it.
 * Even if created with a Platinum Crown, the Slime Crown will always appear to be made out of gold.