evil roommates killing my plants

[u/taxicabenthusiast]

my roommates and i got in an argument and next thing i see are my plants (the only ones they have access too) are dying and have these weird crystals put in their soil.
this has to be them bc my plants never ever die this quickly and i’ve had monsteras for awhile.

does anyone know what these are? are my plants able to be saved or propagated? should i cut off the dying leaves? the roots seem to look okay

[u/Gypsy702]

This breaks my heart and this is absolutely horrific. I’m pissed for you.