They definately aren't manjanos and although they look similar to the sand dwelling nems you often get as hitchers they aren't those either. I found a couple of mediterranean species of aiptasia that they resemble, Aiptasia mutabilis and Aiptasia diaphana so i think they are a species of aiptasia.
It's not just the three on the rock, it is literally covered in them, which is why aiptasia would fit well.
I've kept them in a sealed bag so they can't do any harm, at least until i get a positive id.
My friend has berghia nudis so i may take a piece of the rock and see if they are interested as they are obligate aiptasia predators.
I'll let you know what i find out, unless anyone else could help me out.