A very nice video uploaded by psteeleb shows a vivid specimen of Sunset Montipora. The speaker on the video points out the mesenteric filaments, as he describes as the purple cottony areas. Mesenteric filaments is an increased surface area used for digestion. The mesenteric filaments are also used by a coral that is competing for space with a near by coral. The process also cleans the area adjacent to the coral prior to colonization.