A substance that tends to reduce the surface tension of a liquid in which it is dissolved (took that right from dictionary.com)
I think the answer is "the older it is"
Reason: I might be wrong but is something (like a shell) gets buried in something (like sand), overtime many things (like dirt, soil, sand, etc.) will be on top of the original. This will make layers. So, the older rock is on the bottom since it has been there for the longest and it gets covered by other stuff (causing the layers).
Hope this helps! :) (If I'm wrong, sorry :( )
It cannot survive because an earth worm will not become 2 new worm. The head of the worm may survive and regenerate a tail. But if original tail of the worm may not survive because it will not be able to grow a new head or the rest of its vital organs and it will die. I hope this helps. :)
