the Alien Brain and Pod-Brain are quite clearly based on some of the Tyranid concept art from the latest round of 'nids - which isn't a bad thing,by any means.
I would probably use the Wyrm as something non-tyranid - a dangerous Indigen or some last surviving Megarachnid, maybe. It just doesn't seem sufficiently tyraniddy to me.
I like Troll Forged (especially in concept - I wish I had anything sculpted for them to cast up) but they really don't do anything I'd be interested in buying.