The thing in the picture is a stone cross dating, it is thought, from the first part of the 11th century. It now stands outside the Penlee House museum and art gallery in Penlee Park in the centre of Penzance, although it was moved there relatively recently. It is called the Ricatus Cross, because there is on the side an inscription which may read REGI RICATI CRUX (“the cross of King Ricatus”). It is, however, very difficult to read and other interpretations of it exist.
If this reading and the dating of the cross are correct, it is unlikely that Ricatus was a king ruling over the whole of Cornwall. By the 11th century Cornwall was firmly under the domination of the Saxons. But Ricatus, if he ever existed, may have been a local bigwig with aspirations.
In the 16th century drama Beunans Meriasek (“Life of Saint Meriadoc”) the names of four kings of Cornwall are mentioned. One of these is Pygys, which just could be a misreading for Rygys, and that just could be the Cornish original name on which the latinised Ricatus was based.
It’s a mystery.