Advice on hydroids. Tiny stars covering my glass.
 

Hi, I have a ton of tiny stars on my glass. After googling I found their some type of hydroid. I have tons. When I clean my glass their coving it again within the hour. Their tiny but everywhere.
My question is will they bother corals? My tanks about 5 months old. And I was hoping to add some corals but dont want to if their going to be an issue. I also read the hydroids will die off when they run out of food? I have lots of pods and such.. Will they really die on their own or is their a fish I could buy that might eat the hydroids? I googles but aside from reading that their not good I wasnt finding any information on the impact they have.