Good idea to add better power-up sprites! I just used what I had available.
The cracked rocks should all behave similarly, but maybe that's a bug. I did use the same sprite for decoration within the floor so maybe that's what you're seeing.
The magnet can be a bit risky - it does make it easier to jump on slimes for extra points but the slimes can also just kill you.
Thanks for taking a look at my game!