Fun fact an adder (snake) was once a nadder, and an apron was on a napron. This fun fact brought to you by The History of English Podcast.
https://historyofenglishpodcast.com/
Happily sourced in Wikipedia so I don't have to figure out which episode I learned that from:
https://en.wikipedia.org/wiki/Adder <- see below the table in Taxonomy.
And cherries were ceries from French, leading to the singular form cherry. Lots of neat little things like this.
Swedish does a similar thing where it takes the plural of an English word as the singular Swedish loanword.
Kex = biscuit, from "cakes"
Keps = hat, from "caps"
German does it too: ein Keks = a cookie
And peas was both singular and plural like fish.
"I ate a single peas" "I ate many peas"
People thought it was a mistake and generated "pea" for a new singular.