Board Thread:Plants vs. Zombies 2: It's About Time/@comment-24508466-20140510102339/@comment-9906728-20140511162531

Btw, The graves from that world can : (I could be wrong but according to what, I read, I think this is what they do)

Spawn zombies.

Respawn.(As an event of a level, Like the sandstorms and these things)

All what the regular ones does.

And also they can drop things when destroyed.