Thanks for that.
I am barely sure what I am doing at the moment but think I am making progress. So as I think you mentioned i think I was looking at or messing with separate partitions so I tried to access the device and start over, that is
sudo fdisk /dev/md126
I deleted the two partitions then created a new one and it shows up as md126p1 and automatically with "Linux filesystem" as the type.
I thought that I should then format it:
sudo mkfs.ext4 /dev/md126p1
but it told me:
/dev/md126p1 contains a crypto_LUKS file system
How is that? I mean good i guess, except I didn't setup a crypto_LUKS fs or is that default?
I tried to access it via a VM and it now shows up in nautilus and asked me for a pw (like an encrypted dev i guess) except... I don't know the pw? I tried a pw, it wasn't right, then the dev disapeared from nautilus, i tried detaching/reattaching it, still didn't show up in nautilus.
I am stumped? (though hope I am getting close)