Trygon
The Trygon is a colossal snake-like Tyranid that, when in its upright posture, stands taller than most Tyranid organisms, even the mighty Carnifex. Its body is covered from head to tail with shifting plates of heavy armour, and yet remains incredibly flexible and agile. The creature is able to build up a massive bio-static charge, in these plates, by agitating them as it moves, and then release this energy in a highly lethal discharge.

As if that wasn't enough, the Trygon also comes armed with sets of swift and deadly scything talons and are strong enough to cut through even the heaviest armoured vehicles. The scything talons are not only fearsome weapons, but they allow this monstrous beast to burrow through the hardest of surfaces and create a network of tunnels, before bursting from the ground to inflict devastating attacks on warriors and tanks above. Other Tyranid creatures will often use the network of tunnels left by a Trygon to move unseen underneath the battle above, and the emergence of a Trygon is usually followed by a horde of other smaller organisms.