This is the Spaceborn Creature from the TNG Pilot "Encounter at Farpoint". These creatures can take any form, that's why the Bandi forced one to become Farpoint Station, while another one came to rescue his friend in it's armoured form. In the Star Trek Titan novel "Orion's Hounds" they are called "Star-Jellies". There a race called Pa'haquel hunts them and uses their dead bodies in the armoured form as some sort of spaceships, which they call "Skymounts". ex-astris-scientia.org estimates a diameter of about 1,5km. This would set the scale for this one to 1/20000, as requested by stewpi. This figure is highly conjectural and because these are lifeforms, I believe there could be others with different sizes.
Be aware that the price for Frosted materials Shapeways calculates for this includes a per file and a per part fee. You only have to pay the per part fee for this when I combine this with one or more items in Frosted Ultra/Extreme Detail. So ask me to combine all the items you want to one single file to get it cheaper.
If you need this in another material, size, quantity or combined with one or more of my other parts for cheaper printing, just let me know. I will try to make it as you need.
If you want to see my custom-made Star Trek Tactics ships, visit my thread on hcrealms.com.