| Cornerstone abbreviation |
| Alkaline ecosystems |
| Closed ecosystems |
| Corners of a California ballpark? |
| 552, on a cornerstone |
| Abbr. on many a cornerstone |
| Abbr. on some cornerstones |
| Diamond corners |
| Ecosystem endangered by global warming |
| Ancient Indians of the Four Corners region |
| Tilt dangerously around corners |
| Ecosystem-replicating facility |
| Underwater ecosystem made up of brown algae |
| Places for hospital corners |
| Org. concerned with ecosystems |
| Amazonian ecosystem |
| Protectors of the reef ecosystem? |
| Backyard ecosystem of a sort |
| They're grabbed on corners |
| Some endangered ecosystems |
| Oceanic ecosystem |
| Amazon ecosystem |
| Large ecosystems |
| Ecosystem components |
| Ecosystem |
| Group of similar ecosystems |
| Submarine ecosystems |
| Abbr. on a cornerstone |
| Enclosed ecosystem |
| Ecosystem monitors |