Hi! I just acquired a 75 gal saltwater tank. I’ve had it up and running for about three weeks. It came with about 7 pieces of live rock, two snails, a spiny starfish, a starfish that just moves around under the sand and a hermit crab. Oh and a sea urchin. We replaced the sand and kept a little less than half of the water that was in the tank when we moved it from our friends house to ours. We added 3 clown and 3 damsels the week we got it. And added two pieces of coral and a goby last Sunday. But I just noticed some algae growing and several tube looking things on a piece of the live rock. I’m wondering if it could be dangerous to the fish or coral? Do we try to get rid of it or let it be? Did it come from the coral? Thanks in advance for any advice you have!