Some coral colonies spread across a reef for meters. The Azure Tube Coral has chosen to be compact. Measuring 3.5 by 2 inches, it is a simplified ceramic cluster of tubes glazed in a clear, sky-leaning blue, and one of the smallest pieces in the Coral collection. A single screw holds it, and it fits into gaps on a gallery wall that larger pieces cannot reach. It needs no water, no light schedule and no particular encouragement. It is small, it is blue, and it is very comfortable with both facts.