After realizing that the polyps do seem to extend all the way around the back (wasn't sure at first when I was looking at it on my smaller phone screen) and a bit of browsing frags for sale, I'm guessing those frags will grow into what would now be called a devil's hand leather, which seems to be a blanket term used for a diverse set of morphologies of Lobophytum. A long time ago it was more chunky forms to be "devil's hand" name, while those with longer, narrower projections were usually labeled "finger leathers." However, now I'm seeing a lot of frags sold as "finger" varieties that usually have been sold as a "tree coral" 10+ years ago (some of which are Sinularia, which can be quite a bit more finicky than something like a toadstool leather). Common names do drift over time.
Anyway, I think what you are seeing is a frag formed from one of the upwards projecting bits of a coral like this one I have. Polyps are not fully extended in this picture from this morning, since it just finished a routine slime coat shed yesterday and is still opening back up. But you can see the finger-like projections it has at least.
Obligatory remarks on the topic of blue light: the blue range of the spectrum is still pretty important for reef aquariums, and if you bodge your spectrum it can set the tank to algal bloom problems or stunt coral growth. Some very hardy soft corals can still be grown under a strong regular house lamp bulb that looks white to us but isn't really very well distributed spectrum-wise. However, they will grow better under a spectrum with the right spectrum peaks, at least one of which is in the blue zone. Hence the existence of bulbs specific to marine aquariums and why they have a cooler/bluer look than those intended for freshwater or most household bulbs. Of course, some shops will overdo the blue because excessive blue makes neon colors more neon. That may be what Colin is referring to. I find that type of super-blue lighting to be an eyesore and would never want it myself, but it's popular with Zoanthid enthusiasts. Sometimes it can look overwhelmingly blue to our eyes but still has plenty of the rest of the spectrum to grow corals despite the weird look, similar to how light that looks white to us doesn't necessarily have all the spectrum corals need.
