They used to show me ink blots when I was getting treatment for my condition, and they were just the same as this artefact. I also came to the same conclusions as to the serpent, boat and anchor. Since treatment though, it just looks like random shapes and bulges, dang it.
The hurricane must have made them forget the religious obsession that they were at that time afflicted with, and they stopped cluttering up their artefacts with crosses. They went around digging boat shaped earthworks to educate people centuries later as they didn't have to worry about food or getting out of there.
The only other explanation I would believe, is the one I heard from Cheesh and Chong back in the seventies.
My apologies if any needed - Nuggy