The Foureye is a small passive organism that is biologically two conjoined twins operating as one creature — hence four eyes — and, like the Twin Sitaray, it is always born in pairs. It is one of the most fragile creatures in the game, with only around 5 HP.
It poses no threat. Its interest is ecological and as a scan target: it is common around boundary terrain like The Cliff, where its presence helps signal you are near the edge of the explorable world. Scanning fauna like the Foureye fills out the Data Bank and fleshes out Proteus’s food web.