[dwringer]

The @ is sometimes used like "apples, 50¢ @" in which it is read as "each" rather than "at". This may have faded out once email addresses popularized it as "at", but it always made more sense to me since @ looks like an "ea" ligature.

[IggleSniggle]

Ah, I wasn’t aware of this, but it makes a lot of sense! It even looks like it could be a ligature of “eac”, and it’s very natural to imagine a cursive each being abbreviated first to @h and eventually to just @ by a busy clerk.

[formerly_proven]

German uses à for this purpose, there is probably a shared history behind that.