Ok Petels, That dark blue piece in there was your start piece, it looks like it goes from one side of the cube to another and (probably) didn't actually have much to add. Look at the light blue piece in the 2D, see how there are a bunch of dark lines in there? That's a good indication that several things that don't go together have been put together (coloring inside the lines!) What happened is that the dark blue piece tried to go through the light blue piece, and failed. I assume you couldn't see the outline of the dark blue piece once it hit the light blue? That can happen when there was an error with the staining (when there's not enough dye in a certain area you can't see the outline of the cell, and the AI starts messing up).
Something to keep in mind, these things should look fairly smooth, and it shouldn't look like there's a bunch of separate branches in the same cube (if they're all connected it's one thing, but these all reach across the cube separately).
Keep these coming guys!