I always thought that the species contained by the Interrex to that one planet were a Tyranid strain?
from my understanding, The Mega Arachnids were a highly intelligent race that produced tech for traveling between planets, but didnt really require tech in the form of personal weapons or body armor due to their own physiology being so crazy.
They had thick natural carapace, that could survive space, and there limbs were extremely dangerous.
THe interex destroyed their ships and fleet yards, and destroyed any attempt of them to leave the planet.
until the great crusade showed up and attempt to xenocicde the preserve the interex put up.
there is always a chance more might exist.
and in my mind, the Mega arachnids reselmeed the ambull, except eh ambull was the juevenile stage of the megaarachnids.
Edited by Triszin, 28 May 2018 - 01:46 PM.