Talons
From Exterminatus Manual
++Weapons++
Talons are the basic melee weapons of the Tyranids. Huge blade-like claws they are a serious threat, even to Space Marine power armor. Talons come in many varieties, designed to deal with different threats to the Hive.
In Exterminatus, the Warrior class is armed with a pair of Scything Talons, the stealthy Lictor got its own set of huge talons and the massive Carnifex is armed with two pairs of Monstrous Talons. Only the Zoanthrope and the Termagaunt lack talons altogether, so these classes are relatively weak in close combat.