The Hairy Mushroom (Rhodactis indosinensis) is very easy to maintain and is and a good choice for the beginners. It should be noted that it is somewhat aggressive and can harm sessile invertebrates and overgrow other inhabitants of the reef. 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. Approximate Purchase Size: 3/4" to 1"