Attention! Day Five
The following event, small and quiet, happens on Day 5. When your character wakes up on Day five, there is a small, flat, triangle on the nearest surface to your dominant hand. It's about 3" across. Color is variable, but general a non-color, like gray.
If examined, one side will adhere to skin.
If adhered to skin, like a "patch" type drug, it has the property of allowing a character to understand other spoken languages.
Don't ask how it works, the ways of the Krell science are mysterious. But something has placed it there. Only it may take trial and error on someone's part to discover what it's for. ;-)
If lost or thrown away, it, or another one, will reappear in 2 days.