What is this thing?

No specific insight, but my instinct says it's just a design/decorative choice. Whether you want to use it for pistachios or car keys, the covered section seems like it would affect the aesthetic much more than function since the hole is big enough for a whole hand.

Scrolled through this online museum for arabia stuff but didn't find that design. They don't claim to have everything though, just some 2000+ designs..

http://arabia.kokoelma.fi/etusivu_esittely.aspx

But there should be more info on the bottom to help identify it! Something like this, that would hopefully have name of the series

Edit: found this posting on a Finnish site:

https://www.tori.fi/recommerce/forsale/item/15126547

Still no idea what it's for but it's listed as a bowl. Probably just an art piece of a bowl without a specific purpose. Designer's name is Gunnel Sallmen

Edit2: More info on some Japanese website, no idea how credible. http://www.hamon-okayama.jp/item/583/?mode=pc

Machine translation below:

Manufacturer: ARABIA.
■Series: Art Department Vase.
■Size (cm): φ13, height 3.5.
■Era: 60S.
■Design: Gunnel Salmen.
This is a flat vase made by Arabia's art department, the Art Department. It was designed by Gunnel Salmen. The Arabia Art Department was an art department that did not aim for mass production, but allowed creators to create freely.
Finland's most famous designers, such as Kaj Franck and Kaipianen, were on staff.
The number of pieces produced was very small, making it very rare even in Finland.

Cat bowl?

I have zero experience with pottery or Finland so this is just a guess: possibly a necklace display piece? It has a shape like you'd display a necklace on and the black ovals could be good contrast for jewelry?

Salsa bowl. It stops your drunk guests from tipping it over!