These low light and low flow Mushroom corals make great beginner corals and come in all different colors. Mushrooms that have long tentacles are aggressive toward other types of corals, so provide these corals with adequate space. Please note, that when mushroom corals are shipped, it is perfectly normal for them to be deflated and very small upon arrival. Once adjusted to your aquarium conditions, however, they will fully open. The acclimation process normally takes several days to a week.