Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.
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Question: Fact 1: Echinoderms use pheromones to communicate with each other. 
Fact 2: Modern echinoderms include starfish and sea urchins.

Answer: Starfish use pheromones to communicate with each other.


Question: Fact 1: Insects may live in large colonies and have complex social behaviors. 
Fact 2: Ants and butterflies are insects.

Answer: ants may live in large colonies.


Question: Fact 1: decomposition increases the amount of nutrients in the soil. 
Fact 2: Moisture is needed for bacterial decomposition.

Answer:
bacteria are able to increase the amount of nutrients in the soil.