Cuatrillo
Cuatrillo is a letter of several colonial Mayan alphabets in the Latin script that is based on the digit 4. It was invented by a Franciscan friar, Alonso [de la Parra], in the 16th century to represent the velar ejective consonant found in Mayan languages, and is known as one of the Parra letters.
A derivative of the cuatrillo by adding a diacritic,, was used for the alveolar [ejective affricate] found in the same languages.
As an example of use, the letter appears when spelling the name of the Kʼicheʼ language in the Parra orthography: ꜭiche.