Here's a post by /u/Takeoffdpantsnjaket on the topic.

Wicked dumb question, but, upon reading a little about “croatoan” and the Roanoke islands, the explorer John White had seen a tree with the letters “CRO” carved in it. He had mentioned that if the colonists were distressed, they were to write a cross on a tree as a symbol of their being in distress. What if there was a mix up in the communication, and instead of actually drawing out a cross, they were trying to actually spell “cross” and just never finished the word?