Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
--------
Question: Ocean ridges formed by marine invertebrates living in warm shallow waters within the photic zone of the ocean are called coral reefs.

Answer: Ocean ridges formed by marine invertebrates living in warm shallow waters within the photic zone of the ocean are called what?


Question: There are three quarks in each proton and neutron.

Answer: How many quarks are in each proton and neutron?


Question: Distance is defined as the magnitude or size of displacement between two positions.

Answer:
What property is defined as the magnitude or size of displacement between two positions?