One important piece of machinery in the cell of algae and how that machinery helps keep alage alive

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

you did not give any options thus this is the best answer i can give to you with this little information you have given

> they are both natural and not man made

> they can be tracked and predicted by the right tools

-love shrooms

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter  

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)