Arcane magics! Although if I do a project like this again I'll probably have less completely random stuff like that and more set patterns. Unless you're talking about the ones at the very end of the cave, you'll need dynamite or clever rock breaks through gaining to get in.
Nah i blew up the ones near the end goal with dynamite, the randomized rocks on the way back just always blocked my path by never leaving anything wider than a 2 block gap, so literally 1 size up and i would immediately get stuck, and in some more RNG weirdness and i couldn't get more than 7 pills, and 2 dynamite (so only 1 for the path back). also this is just motherlode without fall damage and i love it.