The link above, by the way, is to Wikipedia, which is a worldwide, collaboratively developed, free encyclopedia. I find this concept to be fascinating, and it’s sort of a fun hobby to help write an encyclopedia.
Lateral voiceless alveolar fricative
So, the letter I "discovered" turns out to be known as the "Lateral voiceless alveolar fricative". My wife gets credit for finding this obscure information. It turns out to be used in Welsh.