– You need to come every other day to feed them, otherwise they die or differentiate. – You have to come on weekends too. – If you are not super super careful, some bacteria or yeast will eat them up. – Even if you are super super careful, some bacteria or yeast will sometimes eat them up. – In experiments, there are huge differences in the behavior of cells so you will have huge errors and have to repeat the experiments multiple times to prove your point.
+ You have to do it, so your other studies are tested on something alive and thus are proved relevant.
That's it. Nothing else to the + list. Cells are bitches. You have to nurture them and pamper them and sacrifice weekends, and then they die or behave unpredictably.
Morphological differences between thorns, spines, and prickles
Ammonite fossil, 45 - 60 mm
Credit: slava__bobrov