рассказана???

[chknkatsu]

in this sentence

"Сказка рассказана бабушкой."
"The fairy-tale is narrated by a grandmother"

why is "рассказана" used? when i look at conjugations of "рассказать" it is not even listed.

i understand its the past tense, why isnt it "рассказа́ла"

http://masterrussian.com/verbs/rasskazivat_rasskazat.htm

[Volk]

Try this way.
"Сказка рассказала бабушкой."
Does it make any sense?
It doesn't.

But:
Сказка рассказала про волшебный горшок.
Or:
Сказка рассказала про старую бабушку.

And:
Сказка рассказана (by) бабушкой.

"The fairy-tale IS narrated BY a grandmother"

I hope my explanation makes sense