Yes, that is Serapis. He was a manufactured diety of the Ptolemaic Dynasty of Greek Egypt, needed to unite Egyptian and Greek Gods together. In this form, he was pure bullshit, it was always known among intellectuals in the ancient world he was a diety of political necessity. Its antecedents prior to this era have little to do with this monstrosity of irreligion. I can’t imagine someone wanting to worship a blantantly obvious false God.