Holder

Holders are a type of purposed organism used by the Harkas from before they had access to teleporter technology.

They were designed to hold a number of items within themselves and travel with harkas in order to carry these items for them across long distances. They could very massively, especially when one takes into consideration the sheer number of environments they might have to travel; some would have to travel on land, some through vast oceans, some might even have to travel in gas giants. Some might even have to move between different areas, e.g. holders being sent to the surface from space. Many holders would be designed for the ultimate long distance haul between planets in space. Some late species of holders had FTL travel capabilities.

Some holders carried items in different ways. Most stored items in a large pouch on their body, but others would store items in their stomach by swallowing them. These would not be able to store anything biological as they would digest it, and would need large stomachs. They needed some complex muscle networks around the stomach to regurgitate specific items for retrieval. However they had the added advantage of almost perfectly guaranteeing the item in question is always with the holder until retrieval.

The harkas themselves can ride in a large enough holder. They usually ride on the exterior for obvious reasons. 

The holders can vary significantly in size. They can span from a few cm in length to transport very small items to several - kilometer beings that would transport massive items between planets. The latter of these often resembled bioships.