Okay, so I've had my tank for about a eight months now and I bought it from a guy who had it up and running for about a year and a half. At first I found a few of these "hitchhikers" on the live rock and thought nothing of it because they were so tiny. However, now they're covering the bank of my tank and they're getting bigger. They're also on my live rock. I'm assuming this is why I haven't had much coraline algae growth on the back glass. What can I do to get rid of these things!?