Sorry
Background:
I received aquacultured live rocks from Florida 6months ago and these were on the rocks, they do retract when stressed. They have a pretty bleu glow on the tip. The rocks were first in my 55 gal and now in my new 92. They seem Very hardy has they have been through a lot when my 55 broke and I had my pets in a bucket for a month (They are all doing great).