I don’t honestly do not know the answer
A simile can be found when using "like" or "as" between two things. Example: I'm as happy as a clown.
Your question would be a metaphor. Both things are being compared to a science expieriment, probably meaning that they need to have an outcome, but it isn't known for sure if it will be a good or bad outcome.
Things like this can be taken many ways, so if you think something else, I'm sure it would work as well.
B.) Garden
this is because "on" is one of many words that are commonly in prepositions. Then to find the object of the preposition, you have to ask yourself, "on {or insert whatever your word is here} what", because the object of your preposition is the subject of the preposition. :)
I hope that makes sense!
