| desert | 0.20 |
| polar regions | 0.16 |
| grow on tree | 0.68 |
| grow on rock | 0.65 |
| consist of algae | 0.53 |
| survive | 0.42 |
| cover tree | 0.42 |
| come in form | 0.42 |
| grow on exposed soils | 0.40 |
| absorb water | 0.40 |
| survive in space | 0.37 |
| come in many colors | 0.35 |
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| sunlight | 0.25 |
| fungus | 0.77 |
| symbiotic organisms | 0.62 |
| composite organism | 0.56 |
| composed of alga | 0.64 |
| composed of fungus | 0.53 |
| identified | 0.48 |
| removed | 0.47 |
| attached | 0.35 |
| responsible for the tree | 0.30 |
| boiled in a solution of… | 0.25 |
| composed of white filam… | 0.25 |
| composed of , rounded c… | 0.25 |
| extracted by urine | 0.25 |
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