This could also be natural asexual fragmentation....many soft corals, either if they are very happy, or somewhat stressed, will start to "self-disintegrate," thus forming frags that will drop to the sand, and will grow into new corals/colonies.
With all due respect to InsaneClownFish, I've never heard of a soft coral being attacked by boring algae.
If it were me, I'd leave them as be. If they start to get necrotic (rot), then I'd remove them as quickly as possible.
My dos pesos,
-R