Tyranids adapt to the Aegis Diamando

• Shield of Baal [Exterminatus]:

"THE NIGHTMARE BEGINS

As has oft happened in the Imperium's long and bloody history, it had under estimated its foe. The hive fleet sailed through the Aegis, encasing itself in vile secretions that quickly froze into diamond-hard armour. This shield not only protected the Tyranids from the unnatural cold but was also proof against the Imperial battlefleet's massed guns."

• Dante:

"The Aegis Diamando was a field of ice that filled the ships oculus and displays. A n uncountable number of objects tinted a rose pink by the light of the Red-Scar. The ices were compress to unimaginable densities by temperatures that somehow exceeded absolute zero. It was a total barrier to Imperial shipping. Anything that attempted passage was frozen out of existence. The Aegis's presence force a risky in system Warp exist. The resources of the Cryptus system had been so vast, that the inevitable losses had been regarded as expectable. It had been hope that it would provide an uncrossable barrier to the Tyranids. The deployment of any military force to Cryptus at all, evidence unusual foresight on the high-lords. The Aegis had not stop the Tyranids nor had the military, Cryptus was dead. Lock into its frozen tomb as Dante warriors were preserve in the sepulchral. Planetoids of super fluids and exotic ices resolve themselves from the mass of objects.

According to Dhrost the hivefleet had pass through. Freezing over with a protective sheet of ice and emerging alive despite its organic nature. If the like of the Aegis can not holt the Tyranid advance nothing could stop them, Dante thought but kept his misgivings to himself. How is it possible my lords that the Tyranids breach the Aegis, he asked instead. Corbulo answered first, the physical explanation is thermoregulation of the Tyranid vessels, but there output would have to be equal of that of a dwarf star. Vessels warm by fusion reactors have frozen solid, killing every soul onboard. The Tyranids do not appear to produce their energy this way. Mere biochemistry could not have warmed them enough. They are dormant as they travel across interstellar space, were the temperature is low but still greater than that of the Aegis. My opinion is that they should have never awaken from their hibernation after passing the Aegis. There's no physical explanation for what they accomplish. The metaphysical explanation my lord of death?, ask Dante of Mephiston. The whole of the Red-Scar is shot through with anomalous phenomena my lord. There is the touch of the Warp upon the Aegis especially, weak but enough to pervert the natural order of the material realm. Perhaps the shadow of the Hivemind afford some additional protection. It's blanketing of the Warp may have divorce the Aegis from whatever cools it so, allowing them passage. That make some sense, said Corbulo. Testing of the region they breach would have to be undertaken to prove your hypostasis. Such work is for the adepts of the adeptus Mechanicus. Not for we Blood Angels, said Mephiston. The Aegis  did not stop them, we must find another way. That is all we need to know."