This is our oldest Acropora. I picked it up in 2001 during my first visit to the Los Angeles wholesalers. For many years we called it an Acropora Gemmifera. After having a few professional hobbyist through the store recently, we agreed it is more likely Acropora Humilis.
Needless to say, it's a slower grower, thick branches, high light and high flow.
Second photo is one of our mother colonies.