It was our first game deployed on WebGL so didn't know how it was going to affect the visuals, even the whole day/night cycle is barely noticeable in this version. We'll have to add Win/Mac Download versions too for the next time.
There are some ways to prevent a slime to enter mitosis and split, but sadly even then when they grow older they enter an elder stage and will eventually die :( You can take good care of them to reduce the mortality rate but some things can't be avoided :(