Several other local historical markers were also hit.
“The defacement of these symbols of Plymouth’s history, or any public property for that matter, is unfathomable and unconscionable,” Town Manager Melissa Arrighi wrote on Facebook.
The vandalism took place Sunday night or early Monday, and cleaning efforts are now underway.
The markings include “508” ― the local area code ― and the letters “MOF.”
Other markings include obscene words, a sad bunny face and five-pointed stars with “666” written around them.
The rock commemorates the supposed landing site of the Pilgrims, or Puritan separatists who left England first for the Netherlands then, in 1620, for the Americas, eventually landing at Plymouth in December of that year.
The community will mark the 400th anniversary of the arrival with a series of events this year.
No rocks at all were mentioned in the documents and descriptions left by the Pilgrims themselves but rather it is a local legend that dates to about a century later and didn’t appear in print until 1775, according to Pilgrim Hall Museum.
The “1620” inscription on the rock was added in 1859.
Plymouth Rock and other local sites have been attacked by vandals in the past, but this one seems more extensive.
Some of those past incidents included political messages, but police told USA Today there doesn’t seem to be any political motivation behind the current wave of graffiti.