How did you get the pearl 'off screen'? You mean to a different part of the map? Because if you do, then it should still be around somewhere. Although leaving and coming back would reset it.
I think the problem is:
*Spoilers (if you don't want to read them, just suffice it to say that you need nature form)*
You need nature form's seeds to open those red plants which contain pearls. Assuming I know the place you mean, if you go up and left then there are plants which, when bumped, drop seeds. It is possible to get those seeds caught in the currents to the right of the plants, which will drop the seeds on the field of red pearl plants. In this way, you can get the pearl before getting nature form. When I played I got this by accident, you may have also done what I did. If that is the case, you got a pearl, but since you lost it (somehow) and left, the pearl will be back inside the plant (if you don't get it to the holder before leaving the map it resets).
*/spoilers*
