Complex sentence: Gruenwald was famous for a seemingly near-perfect recollection of even the most trivial details; an annual contest where fans tried to stump him with obscure questions was eventually discontinued by Marvel as it became clear he would never lose.
Split into simpler sentences: Gruenwald was famous for a seemingly near-perfect recollection of even the most trivial details. An annual contest where fans tried to stump him with obscure questions was eventually discontinued by Marvel as it became clear he would never lose.