Creature Log
An in-game log of every creature caught so far, opened with the Tab key, so players can check what they still need to catch.
A Steam Community screenshot shows the in-game tutorial tooltip verbatim: "You might forget which creatures you've already caught. Try thinking by pressing [Tab]." This lines up with the official achievements "Collector" (find and kill every creature) and "Fishipedia" (find and kill every drip creature), which describe the same completionist system.