Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

[Q]: In invertebrates group of animals several forms of asexual reproduction are found.
[A]: In what group of animals several forms of asexual reproduction are found?


[Q]: Deep currents are caused by differences in density at the top and bottom of the ocean.
[A]: What is caused by differences in density at the top and bottom of the ocean?


[Q]: Meteorites are often comprised of remnants of the earliest material that formed in the solar system.
[A]:
What astronomical phenomenon is often comprised of remnants of the earliest material that formed in the solar system?