Our first discovery

I bought some rock to put in the tank. It has 2 purposes. the first is to just be something interesting to look at, the second is to act as the primary method of filtration for the tank. It's called Live Rock because of all the algae and bacteria that live in the cracks and pores of the rock. This rock can be home grown, but tyipcally is is harvested just of reefs at various worldwide locations. If you're interested in explaining how this works to the kids, look up "The Nitrogen Cycle" on line. The short story is critters poop and stuff dies, this creates ammonia. certain bacteria eat ammonia and create nitrites, other bacteria eat that and create nitrates. Plants eat the nitrates. Critters eat the plants and the cycle starts all over again. That's part of the draw to this hobby, trying to maintain the balance of this tiny ecosystem in a bottle.
Occasionally you will find more interesting critters hitch hiking on the rock as well. I once had a crab sneak home with me on one of these rocks. This one wasn't quite as interesting, but the kids were excited to make the discovery. On one of the rocks was a little maroon button. After the water began to clear from the addition of the rock and it all sat under the lights for the day, the button opened up. It looks to be some type of simple life form, plant or coral maybe. Post a comment if you recognize the thing.