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.

Fact 1: Protozoa can be classified on the basis of how they move. 
Fact 2: Cryptosporidium parvum is the hardest protozoa to kill.
Animals like cyptosporidium are often classified on how they move.

Fact 1: Earth 's magnetic patterns are used for finding locations by animals that migrate. 
Fact 2: Spring and fall migrations of birds and fish animate the landscape.
Earth's magnetic patterns are used for finding locations of birds and fish.

Fact 1: Competition may lead to aggressive behaviors or displays of aggression. 
Fact 2: Frequently their behavior is aggressively hostile.

Competition may lead to hostility.