Greetings All

I am working on the prologue to Snorri's Edda and came across an
interesting line about elephants. It is when the Trojan prince Thorr
is being described (lines 38-40) - where he is described as

"Sva var hann fagr alitum er hann kom meth othrum monnum sem tha er
fils bein er grafit i eik"

Which I translate as

He was so fair in appearence that he came among other people as if he
were like the ivy of the elephant inlaid with oak (strong, towering?)

"fils" in Zoega is translated as elephant - does anyone know the
origin of this word.

Is there any other instance of fils being used in the eddas or sagas?

Thanks, Andy