I recently moved some plants from one greenhouse to another. The original home had no bugs other than beneficial mites in the soil. Two days after the move to the new greenhouse, I found this on one of the leaves. I have also seen some on the top of two of my outdoor tomatoes. None of my farmer friends are familiar with them and one suggested I reach out to you. They are about 1/2 the size of a grain of rice. The close ups are using a digital microscope.