There are 3 slime spawners hidden in the world . 

I will only give these clues:

• They are within the POSITIVE coordinates.
• One is in a Sparce Jungle (Found by Hawkeye)
• One rests at twin peaks in the plains. (Found by Hernrob)
• One has sought to escape the badlands and move to the desert.  (Found by Moah)
• None are "hidden" (they aren't buried or inside chests, they are visible to the world.)