Tiny green bubbles... large green bubbles... elongated bubbles -- all called Valonia. They are a single cell algae that grow where light is present. The fluid inside contains spores to grow more, so care should be given during removal so as not to pop the bubbles and release the spores. Some fish eat Valonia (Foxface & Naso Tangs), as do Emerald Crabs. This is a pest algae and should be removed if possible. If a large patch is present, it can be removed as a cluster.
Photo by Snorkeler