For those who don't know, the Alpha Squad is the very first group of knights to explore the CWs and make it to the core. Because the Skylark's comlink was dead, they had to leave recording modules in their wake (the boss levels).
The one at the core says the entered the core as it opened. Judging by how the last level of the Apocrea mission is at Depth 30, I found a group of dead knights lying around, and there happened to be 4 count 'em 4 of them lyring around. One of which had a tailed helm.
Here's some screens:
WARNING: Spoilers ahead! Do not look at these until you have done the apocrea mission at least once!
http://steamcommunity.com/sharedfiles/filedetails/?id=188587301
http://steamcommunity.com/sharedfiles/filedetails/?id=188587317
http://steamcommunity.com/sharedfiles/filedetails/?id=188587326.
Yet this isn't what the core would look like. I mean, it's full of energy. The stuff we've been using before the Battle Sprites. Unless It's something far different/worse O.o Yet I have also taken account to the theory that this is a depth NEAR the core. Not inside it. I mean, it's in the very center of Cradle. You can't not expect them gears n' geo-globes to be in every nook and cranny!
No....Alpha Squad got lost/eaten/killed/touched/massaged inside of the Core.
These are just random grunts that got tentacle...and teleported to some random (deep) depth (perhaps near the core?)