Naturally occurring rocks
| Natural Area | # snails | #snails/sq cm |
| 38.5 | 361 | 9.38 |
| 24.75 | 87 | 3.52 |
| 45 | 268 | 5.96 |
| mean | 6.28 | |
| variance | 8.669354883 | |
| std dev. | 2.944376824 |
Experimentally Placed Rocks
| Unnatural Area | # snails | # snails/sq. cm |
| 63.75 | 327 | 5.13 |
| 32.5 | 202 | 6.22 |
| 52.5 | 225 | 4.29 |
| mean | 5.21 | |
| variance | 0.935798342 | |
| std dev. | 0.967366705 |