Caligula (37–41). As for Agrippa, N/A (37–41), Rome.

Av. M. AGRIPPA L. - F. COS. III. Bust facing left, wearing the rostral crown.
Rev. S - C. Neptune, nude, standing facing left, cloak draped over his shoulders, holding a small dolphin in his right hand and a vertical trident in his left hand.
RIC.58; Bronze - 12.59 g - 28 mm - 7 h
From the Numismatik Naumann 74 auction, February 3, 2019, lot no. 272.
Minted under Caligula for Marcus Vipsanius Agrippa (63 BC–12 BC), his maternal grandfather. The powerful strike is slightly off-center. Only minimal corrosion on the reverse. Beautiful glossy black patina. Superb.