The turtles are a must have accessory since Adrien sold the turtles to Rocky, which sparked their romantic love story and fueled his motivation to "go the distance."
I thought I read an article recently that the original turtles from the movie are still alive, with the pet shop owner.
I own the original KP Rocky but decided to get the Ultimate for all the extra accessories (diorama, Butkus, turtles, etc).
Also, hopefully the extra sculpt(s) in this set are compatible with the Star Ace Rocky 2 - that sculpt is a hot mess but I like the rest of the figure.