Caveats apply to the following advice, of course, like "it varies tremendously depending on the species and the individual specimen" and "the bigger the tank, the safer everyone will be" but please keep in mind that this is a bit like saying "what victims will be safe with a serial killer?"
Anything with a hard shell (big snails, feather dusters) will likely be safe from a spearing type, as well as sea urchins. I can't think of a type of invertebrate that wouldn't be somewhat at risk with a smashing type. In a big tank, if it's well fed, it may leave more things alone, until one day it doesn't and you lose an invertebrate.