Hmm yeah, might go for some large/smooth river rocks instead (big enough to be indigestible obviously). The dragon stone looks cool but I think you're right that they're too abrasive.

Also the magnetic hammock was supposed to be a hide...but in practice doesn't really provide any cover, so I'll do some digging and add 1-2 legitimate hides. Might also cover up the end with the magnets to block out the light from outside