Why did Constantine send Maxentius’ head to north Africa?

I have been reading about Constantine. Mostly, I’ve been reading John Julius Norwich’s Byzantium: The Early Centuries for the prose. A wonderful writer. I’m a Roman nerd so as I was reading along, I really wasn’t paying close attention to Norwich’s discussion of the battle of Milvian Bridge–for Rome nerds, it’s pretty standard fare. Nerds know the intrigues, but for non-nerds, some short background: Maxentius contested Constantine’s ascension to the purple. It did not end well for Maxentius.

This bit caught my eye:

Among the last was the usurper’s himself, whose body was later found washed up on the bank. His severed head, stuck on a lance, was carried aloft before Constantine as he entered Rome in triumph the following day. Later it was sent on to North Africa as a warning.

You have to feel for the courier who wound up having to schlepp that baby to north Africa, don’t you? Bound to be a rather niffy endeavor. The battle took place I believe in October, if I remember my reading properly. Milvian Bridge is still there, so they only had to go 10 miles to Rome to go head-brandish there.

The average temperature is 82 degrees F in south Italy during October, according the various travel websites I perused. I’m pretty sure back then they didn’t have any Tupperware. Maybe a clay pot with a seal on the top, but a severed head sealed away in a clay pot isn’t going to impress anybody. You can’t walk around and say to people to take you on your word, you have the severed head of a pretender to the purple in this here clay pot so don’t get any ideas about challenging Constantine. One would have to brandish the actual head, wouldn’t one? And one wonders how recognizable Maxentius would be after all that travel in 80 degree weather.

And, notably, whom was the deterrent supposed to be for? I know of nobody there in north Africa who was a particularly worrisome rival; I don’t think Maxentius would have had any power base there (unless I am confused) as I thought he was from the areas in what are now Serbia and Bulgaria.

Anybody know?