Why is a raven like a writing-desk?

My daughter refuses to rest until she has a definitive punch-line to this joke.

Her best offering:
They both come from trees.

I have suggested:
Because Poe wrote on both

Dodgson himself suggested:
because they can both produce a few notes, although they are all flat.

Please feel free to add.

Because both have legs.

Because both have ink on them.

Because you can’t hide an elephant in either of them.

Quoting wikipedia:
“A mature Common Raven is between 56 and 69 cm (22 to 27 inches) in length, with a wingspan of 115 to 130 cm (45 to 51 in).”

These are very ideal dimensions for the table top of a good writing desk! (Cannot be a coincidence…)

They both need a LOT of tomato ketchup to make them taste nice?

… You may be on to something!