You can find very colorful Zoanthids, like this one. I got about 4 polyps (each about the size of pepper corn or ball bearing) and affixed them to the rock with Super Glue Gel. With orange centers and neon green tentacles, they make a real splash of color in your tank. Unfortunately for me, within days my hermit crabs decided they were too tasty and consumed all but one. That can be frustrating because it takes time for new buds to appear.