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.

Q: Fact 1: Echinoderms use pheromones to communicate with each other. 
Fact 2: Modern echinoderms include starfish and sea urchins.

A: Starfish use pheromones to communicate with each other.
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Q: Fact 1: a delta is formed by deposition of sediment at the mouth of a river by water fanning out. 
Fact 2: Erosion is responsible for wearing down exposed places and depositing sediment in level places.

A: a delta is formed by erosion.
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Q: Fact 1: Arthropods are the largest phylum of invertebrates. 
Fact 2: Insects are in the phylum Arthropoda.

A:
insects are arthropods.
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