Help Me Solve A Mystery Coin

OK, I like to think I'm pretty good at solving these ancient Roman coin IDs, but this one recently bought in the same sale as my Hadrian sestertius has humbled me.

Though it appears to have been zapped (cleaned by electrolysis) long ago, there's quite a lit of legible detail left, which should give plenty of hints as to who, what and when. Only none of my usual tricks have worked.



Obverse:
The bare head of the Emperor(?) ("bare" as in without laurel wreath or radiate crown). The portrait is early (pre-200 AD), but I can't pick it - I can't even tell if this guy has a beard, or just some corrosion on his chin. The combination of wear and poor centring means the only legible part of the legend is "...C CAESAR...", which doesn't really help much, except to say it's definitely Latin - so it's from either Rome proper or a Latin-speaking Roman Provincial.

Reverse:
Roman high-priestly implements, from left to right: a secespita, or sacrificial knife; an aspergillum, a whip-like object for sprinkling water; a praefericulum, the jug which stored sacrificial wine; a lituus, a spiral-shaped short staff used to divine omens from the flightpath of birds; and a simpulum, a ladle-like object used to sample and pour out liquids being sacrificed. Apart from the big bold SC, the reverse legend is mostly gone, but probably says either PM T... or PONT... on the left hand side.

What really puzzles me about it is the contradiction between the obverse and reverse. The high priestly office (Pontifex Maximus) was almost always held by the Emperor himself, while the bare head and use of the full word "caesar" indicate to me the portrait isn't that of a reigning Emperor, but the heir-designate or other family member.

All opinions welcome.