Rhodactis 

Easy

Peaceful

Indian Ocean, Pacific Ocean (typically collected off the coast of Australlia and around numerous different Indo-Pacific islands)

Discosomidae

Soft Coral

Rhodactis mushrooms, are not in fact corals, they are Corallimorphs and are closely related to sea anemones. They come in every color and often have beautiful patterns of spots and stripes on them, some of which will even form small bubbles on their flesh and are called "bounce' mushrooms.
They are also found in a variety of different sizes ranging from small 1" bullseye mushrooms, up to 12-18" massive elephant ear mushrooms. A couple of our favorites are the ones known as "pincushion mushrooms" and "bounce mushrooms".
These mushrooms like low to moderate light, but we recommend keeping them in low flow due to the fact that higher flow rates can irritate them and cause them to detach from the rock they're on and float around the tank. Once this happens the mushroom may "melt" or die because they are not so great at re-attaching themselves once they have detached.
Rhodactis mushrooms are mainly photosynthetic, relying on the products of their zooxanthellae, but you can feed them phytoplankton and zooplankton, as well as other products like Coral Feast and Reef Energy if you desire.

Of course, you should always maintain proper water parameters by maintaining good calcium, magnesium, and alkalinity levels.