These are the higher level xzomits found in the NW and NE regions of Al'taieu. In contrast to the lower level Ul'xzomits, which travel in groups of 3, these higher level Om'xzomits roam alone.
The lower level Ul'xzomits will link, in that the two smaller ones ('babies') link strongly to their leader ('mother'). However, the higher level Om'xzomits do not link to one another. I have been killing them for around 5 hours on my BST over the last few evenings, and have never seen a link of any kind.
Drop rate for xzomit organs from these is approximately 10% in the absence of TH, I got 2 in around an hour last night. No idea about the HQ organs, not seen any drop recently.
Hope this helps.
Edited, Feb 6th 2008 11:04am by midnightjade