Go to the line of red pearl plants in the Kelp Forest. Directly above them is a fast current, follow that current backwards up a passageway and take the left fork. As you come out of the current there is a series of little pods on strings attached to the ground.
As you dash by those pods, they'll release seeds. Or plants, or flowers, or whatever they are; the main point is that you can follow them through the current and eventually one will drop on a pearl plant and open it up. Saving you the need to come back later with Nature form.