CROSSING OVER
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A search method employed by two or more people overlapping separate line searches forming a grid.
Not to sure tho hope this helps
In the early stages the embryos of four different species will look the same .For example, fish embryos and human embryos both have gill slits. In fish they develop into gills, but in humans they disappear before birth. That what makes them different.
Using energy is the answer to this question :)