For this scene, it will be a close-up of the blood vessels flowing through the vein.
This was done with a simple Pipe polygon. I did the UV unwrapping first while it was still a straight pipe (much simpler that way) then I used the rotate and scale tool to shape it into a more organic shape. I wanted the open end to be exaggerated, so I scaled it up.
Lastly I used a sphere which I scaled down into a “squished” shape, then pulled vertices down to make it even more concave. The Paint Selection tool worked great for selecting just the vertices I wanted, and Soft Selection gave it a softer shape when I pushed them down into a concave shape.
Overall this scene came together very quickly.