Pipe Organs are an easy coral but they also need some stability for Cal and Alk.  They do have a small skeleton which you need to watch those parameters to be in check.  They are not a fast grower which is nice compare to Green Star Polyps that can overtake a tank.  Keep them at the bottom of your tank because they do not need much lighting or flow.
 
Requirements
Lighting: Low  about 100par
Flow:  Low/Medium
Cal 400-440, Alkalinity between 7.5-8 Dkh, Mg 1400