What are these

[Coralfornialiving]

I see these growing in my boys tank and was wondering what these were

 

[twilliard]

Aiptasia is what I would say
I would superglue them before they get out of hand

 

[Rob.D]

Aptaisia anemones but they might be mojanos. ...pests.

 

[redfishbluefish]

Aiptasia. Take a coffee cup of tank water and boil it in the microwave. Using a turkey baster, cook those little SOBs with the boiling water.

 

[4FordFamily]

Those are mojanos.