[Contexti]

The Finnish word for walrus, mursu, was borrowed into Finnish from Sámi, as mentioned in the WordSense article. The Northern Sámi word morša is likely a loanword from some Palaeo-Laplandic language, borrowed when the Proto-Sámi language spread to Lapland during the Iron Age.[1]

As there are no walruses in Finland, it was nearly as mysterious a creature as an elephant to Finns, who mostly encountered only walrus tusks and walrus hides through trading.[2]

Russian borrowed the word for walrus морж from some Sámi or some Finnic language, as the Russian expansion to the Arctic Ocean is historically much later than the Sámi and Finnic settlement in the area. [2] From Russian, the word got borrowed into French as morse.

Btw, you had a typo in the name of the animal. marsu means "a guinea pig" in Finnish, borrowed from Swedish marsvin (literally "a sea pig"), which in turn comes from German.

[1](https://www.sgr.fi/sust/sust266/sust266_aikio.pdf) [2](https://journal.fi/virittaja/article/view/40611)