| Fossil oligochaetes are much rarer, and there are almost no fossil hirudineans known. |
| Bombing birds' nests is actually a boon for bird-watchers, since the ones that survive become rarer, and more exciting to spot. |
| Such a direct riposte is rare and the opportunity to make it courteously and publicly, rarer still. |
| When you move down the periodic table, as the atomic numbers increase, the elements become rarer. |
| It lists all the rarer plants of the district, and the zoophytes, and devotes a whole chapter to geology. |
| Sea campion, thrift and bird's-foot trefoil flourish here alongside many rarer plants such as sea kale, sea pea and sea heath. |
