There's a short story by Stanislaw Lem (who also wrote Solaris ) about scientists who train a slime mold to be intelligent by forcing it to grow only in the shape of letters, then forcing the letters to be real words, ... and so on, until they able to have full (if slow) conversations with humans.

I just realized, it's kind of presciently like training an LLM. Story is at least 40 years old, so...