Answer to Question 1
Meteorites are fragments of parent bodies that were large enough to grow hot from radioactive decay or other processes. They then melted and differentiated to form iron-nickel cores, and rocky mantles and crusts. The molten iron cores were well insulated by thick, rocky mantles resulting in very slow cooling of the iron core and producing Widmansttten patterns. Collisions could break up such differentiated bodies and produce different kids of meteorites.
Answer to Question 2
Yes. Faint comets are common; several dozen are discovered each year. Truly bright comets appear about once per decade. An average person might see five or ten bright comets in a lifetime. Astronomers do not know exactly how many, but there could be one hundred billion in the Oort cloud.
Cross-pollination and selfing are two types of crosses
The three types of muscles: skeletal, smooth, and cardiac.
Evolutionary tree derived from amino acid sequence comparisons
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There are many types of adaptive devices: (A) a toothbrush; (B) a reaching stick; (C) a shoe holder; ...
The three types of muscle: Skeletal, cardiac, and smooth.