love it, but where is ghost ball? – Infinite Pool Review

I play this game a lot, fun quick way to pass some time. However with new update there is a "ghost ball" added, and the mission I'm currently on requires "pocket 2 ghost balls in 1 game." The issue is I've played a lot after updating and still haven't encountered 1 ghost ball. Not even sure what to look for. Is the idea that they are invisible until struck, or am I missing something?
Review by PedestrianFunk on Infinite Pool.