Psuedocorynactis caribbeorum/ white ball corallimorph.
That's them! They look clear and whitish. It does seem, now that the seahorses have arrived that they don't bother the adults. After reading the description that you linked I might have a problem with fry and them though. I'll scrape out the 2 I can see and reach, and hope for the best on the other one @ the bottom.
Thanks for the link!