Antoninus Pius and Marcus Aurelius, as Caesar. AE Sestertius. 140-144 AD. 

ANTONINVS AVG PI-VS P P TR P COS III, laureate and draped bust of Antoninus Pius right / AVRELIVS CAESAR AVG PII F COS, S C in exergue, bare head of Marcus Aurelius right, slight drapery on left shoulder. RIC III 1219. RIC_1219

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With permission of Heritage World Coin Auctions, Jan. 2013, lot 
21400, sold for $1,000,