It's pale and crumpled, a few yards across. It hadn't really looked like a heart when they'd come across it the first time, when the worm had squirmed it's way free, but the wrinkled grey mass it is now looks quite a bit like a collapsed organ.

The disgust on Rachel's dragon face is similar to Tobias'.

<I don't know. It's what the worm thing came out of. It's what we were attacking when the building went down. More importantly, it's the only thing that doesn't reek.>

That alone makes it kind of special.