Name that invertebrate

Agenda's "50 words or less" question this week:

"What sort of mollusc is Don Brash?"

Update (11/07/04): Having thought about this, I have the answer: he's a clam. It's the way that, when pressed for actual policy details, or about the factual basis of his claims, he clamps his jaws tightly shut and emits an "nnnnnnnn" noise.