Good cut, good cut! Now just clear away the integument, and there we go! It takes a steady hand to get the outermost portion of the body to come out cleanly, but once you've cleared the few bits of connnecting tissue away, you can just split the two halves of the shell apart from each other. Calling it a shell is actually a bit of a misnomer, a closer analogue would be to call it an exoskeleton. At any rate, it's the outermost of three germ layers.
Yes, it looked roughly bilaterally symmetrical on the outside, but now that we're inside we can discern the distinctive body structure of a Spiculid of the phylum Spirulina. As you saw when removing the 'shell', the outer structure isn't very well-connected to the body's interior. That's because the Fossornatus' body slides around inside, coiling as it grows. If it were anchored in more locations, it would be unable to grow into the distinctive pattern that reveals it as a Spirulid.
Now, let's see what we can identify in here. Let's start with the dull purple spiral. This is what we call the coil, the central tube of a Spirulid's body. This one contains a long, thin, digestive tract, and the primary nerve tract.
Alright, now trace your finger right along the coil. See how the orange paddles are directly attached to it? In fact, the mouth, the sensory organs and every single paddle are attached to the outermost half-turn of the coil. As this animal grows, its rearmost paddles will undergo apoptosis, or pre-programmed cell death- just like the process that causes your fingers to get 'carved' out from embryonic mitts. At any rate, the body effectively digests this worn-out limb while growing a new one in the front. The recovered material from the digested paddle becomes... anyone?
Yes, the green stuff. These paired green bulbs you see are the auxiliary stomachs found in all Spirulids. They're little digestive engines, excellent at breaking down and absorbing nutrients. Now, this can be a bit tricky... and kind of sticky, but if you scrape your cutting tool along the coil- lightly, so you don't cut it- you can remove these stomachs, and get a better look at what else there is underneath.
DAFTy 
That was awesome, Iggy, you should do more of those.
