Does anyone know what these are?

[SaltyB]

I woke up one morning and I have hundreds of these all over my reef some are even growing on some of my corals.Are they corals ? Are they good or bad for my tank?What are they? There was just an explosion of them one day!

 

[Paul B]

Most of them are Majanos and some look like aiptasia. Neither of them is good. There are ways to eliminate them but you have so many, it will take a while

 

[encrustingacro]

Exaiptasia diaphana, commonly misidentified as Aiptasia by the hobby.

Most of them are Majanos and some look like aiptasia. Neither of them is good. There are ways to eliminate them but you have so many, it will take a while

None of them look like Anemonia manjano to me; A. manjano has green bulb-like tentacle tips and a dark oral disc.