How big can Aiptasia get?

[Atoll on me]

I was on vacation and saw what seemed to be an old tank with aiptasia. The tank was great, but I was surprised to see the size of the aiptasia in the tank. How big can these nems get?

 

[Red_Beard]

bigger than that :)

 

[William Bruckmann]

Half dollar size for a mature well fed Aiptasia. Quarter size is typical though.