Another room features a mural with two men seemingly offering coins.

In the middle of the very same room, the ancient equivalent of a piggy bank can be found on a plinth - coin slot included.

One can be found in a room full of heads.

The other can be found by feeding the hungry.

Take another good look around the various rooms - one of them features a hungry creature.

The room closest to the 'piggy bank' room has a familiar face in it - Herbert the cat.

He's starving, or engaging in the classic cat behaviour of pretending to be hungry to get more food.

Cats are carnivores, so meat would be the most sensible option.

Feed Herbert the hand we got from one of the cranks in the head room, and he'll reward you with a coin.

Before you leave, take the object shining in the hands of the left statue, too.

Put the two coins in the 'piggy bank', then look at the plinth it was sitting on - we have another puzzle to solve.

Four letters can be pushed in before the puzzle resets, so pressing the 'correct' ones seems to be the objective.

Father's journal may prove useful.

Father's journal mentions the following symbols:

RHO (represented by the letter P) THETA (with no representation) EPSILON (represented by a jagged, backwards '3') XI (with no representation)

While it seems like knowing Greek symbols is mandatory to solving the puzzle, it's worth pointing out that 'A' and 'B' symbols are repeated - but not needed.

Similarly, upside-down 'V' symbols are often featured, but not needed.

See the quickhint below to see the symbols you must press (in any order.)

Don't forget to grab both items that are revealed when the puzzle is solved.

The piggy bank wasn't the only thing in the room - on the left side, a wheel puzzle awaits.