ID this: corals, hydroids or else?

[dendro982]

Help to ID the new growth, that appeared on the well lit sides of my Christmas tree rocks (first 2 photos - on one rock, 2 others - on another, are they the same?):

The size is around 1/8" or 3mm in diameter, 8 tentacles, short stalk, grow in groups, covering already around 1" or 2.5 cm space.

What is it, good or bad, what should I do with them - remove? If so, how - scratching off or using the Kalkwasser paste, as for aiptasia?

Thank you.

 

[mamagoose45]

I have no idea, but at first glance, the second two pictures look a lot like clove polyps.

 

[dendro982]

Actually, much darker and uneven color, and a very short stalk - less, than diameter of polyp.
They look not bad - only I worry, if they will try to take over porites - I see on the bottom pictures, that the smallest porites extended tentacles in their direction, this is the first time I had seen their tentacles at all.