Judging by the photo you provided I'm still leaning toward acan's, but not seeing them in person they may very well be blasto's (or even some other sort of LPS).
The feeder tentacles of blastomussa wellsi are short and are located long the outer edges of the polyp and aren't very effective (when blasto's capture food the entire polyp envelops the food item. I guess you could consider their tentacles to be thorn like. Are your coral's tentacles very similar to the one's in the 2nd photo?
Acan feeder tentacles originate closer to the center of the polyp. If they patterned like the blasto's in website photo that you provided, the feeders would extend from the inner green ring margin. Acan feeder's are longer and more effective at prey capture than blasto's are (the feeders catch the food and guide them into the mouth).