Any idea what the stickers represent on Michigan Football helmets

Michigan Football Uniform Timeline — - Michigan Football History

Photo: New Ohio State concept football helmet designs - Big Ten Network

The Tradition Behind the Buckeye Sticker on Ohio State Football Helmets, by Brad Kern

Time and Change: Ohio State's Buckeye Leaf Helmet Stickers, The First of Their Kind

Michigan Football Uniform Timeline — - Michigan Football History

Ranking the Big Ten's best, worst helmets; where do Michigan, Michigan State fit?

Petition to do reverse color helmets!! : r/MichiganWolverines

Definitive rankings for every football helmet in the Mountain West - The Utah Statesman

Michigan Wolverines: What are the stickers on the College Football Helmets?

Ranking the Big Ten helmets from worst to first – Buckeyes Wire