What on earth is a 1,900-year-old Roman grave marker doing in a US garden?

An American family cleaning up their overgrown backyard in New Orleans made an extremely unusual find: under the weeds was a mysterious marble tablet with Latin characters that included the phrase “spirits of the dead”.
“The fact that it was in Latin that really just gave us pause, right?” said Daniella Santoro, a Tulane University anthropologist. “I mean, you see something like that and you say, ‘OK, this is not an ordinary thing’.”
Intrigued and slightly alarmed, Santoro reached out to her…