Accepted Answer. The Dragon Scale can be found on wild Horsea, Seadra, Dratini, and Dragonair. The only hitch to your plan is that you can only find them after getting the National Dex and Dratini and Dragonair can only be found by using the Super Rod, behind the Waterfall, at Mt. Coronet.
Microtubules are conveyer belts inside the cells. They move vesicles, granules, organelles like mitochondria, and chromosomes via special attachment proteins. They also serve a cytoskeletal role. Structurally, they are linear polymers of tubulin which is a globular protein.
Thus the microtubule end can be thought of as a molecular machine. Because microtubules grow and shrink by addition and loss of subunits from their ends, coupling of microtubule pulling and pushing to mechanical work can be distilled to the problem of the nature and control of the plus end of the microtubule.