Elephant Ball is one of the three skins released under the 'Angry' part of the Pet Balls offer. It was available for purchase in early June 2017.
Elephant Ball could be purchased for $4.99 in a deal that included 3250 coins. It could also be purchased for $19.99 in a deal that included the Pig Ball skin and either 50000 coins (Browser) or 1800 DNA (Mobile). It was not available for individual purchase and may not be available for purchase in the future.
Details of this offer may vary depending on location and platform.