Identify mystery chest

I have acquired a wooden chest with nice paneling details both inside and outside. There are two removable trays that also slide inside the chest. Perhaps the most puzzling details are two slits that are visible only when the chest is open. The slits are 13 cm and 60 cm wide but the opening is only 1-2 mm. Both are roughly 6 cm deep and both are connected to a small hole. On the side of the chest there is a sticker that says Norddeutcher Lloyd Bremen and "Steerage". Photos of the chest can be found here: https://photos.app.goo.gl/a8j5FGAXuit6bnmH9 Is this a "only" an emigrant chest or could this have been a part of the ships interior? Do you have knowledge or ideas?