The shape of those looks more like caterpillar droppings (frass) than galls to me, though I've never seen them so green or shiny. Here's an image of tomato hornworm droppings, it looks quite similar to your picture: ![Caterpillar droppings on a leaf from the website If the balls are firmly attached to the leaf then they are galls, if they can be dislodged, then poop is more likely.