Capnellas are nephtheas but are a different genus, the polyp size and the sclerite structures around the polyps are what separates them. I would call yours a capnella based on polyp size and the lack of sclerite density near the poyps, which you can see in weelo111's pics. The only way to truly know is to look at the sclerite structure under a microscope, either way you have a nice soft coral.