After poking around a bit you can find these popping up as Mycetic Spores for 'Nids. Now this type, the plasma hatcher, is pretty popular. It has all the details one could want with a minimum of converting. Propulsion type tubes at the top, hatch like spots for openings, and has a rough footprint of a 40mm base.
I say minimum because to use said pod at a GW store you'll need to slap some GW bits on it to make it "official". Otherwise, they won't let you play with your nicely painted model you made an effort to get and they haven't released an official version yet... screwy ain't it?
The best part about this type of toy is that you can find it on sale at one chain store in town, then chances are it's on sale at the other locations. So being at Target with the family the other day, the daughter had money to burn, I spy this...
Now these, to me, are more effective as Mycetic Spores. I don't think all of the outside of a pod would be crusty, certainly the nose end of it would be so it wouldn't burn up on entry. With a little bit of super glue, green stuff, and extra bits this will work wonderfully. The bonus here was that they were on sale, two for the price of one pod from Chapterhouse. Deal. Even better, my wife and daughter found two more at another Target and picked them up for me! They follow the dimensions for a SM Drop Pod, about 6 1/2 inches tall by 5 inches at the widest diameter. A Trygon can stand behind it no problem, it's about 1/2-3/4 of an inch shorter than the pod. Putting it on a 60mm base will stabilize it and give a solid reference for the lashing tentacles of the pod. Now I know that this type of stand in modeling is a little easier to do with Tyranids, but have you guys found anything like this for your SM, CSM, IG, or even Eldar? Either outside model ranges or outside of models all together?