Turtle room

In the Turtle room, the HOS on the piano shows a clam that you have to open to get the pearl. I cannot find the knife. I checked the Walkthrough too but it does not give much on the HOS.

Hi there ladyvon4,
In this game you often have to use items in your Inventory to complete a H0 scene, so click on the Inventory tab to see if you are carrying the required item.

If it is not there, it means you need to back out of the H0 scene and complete a few more tasks to acquire what you need. This is another neat (but maybe frustrating) aspect of this game.

You might also seem to be carrying an item for a long time before you get to use it, and also come across a H0 scene earlier than you can complete it.

Enjoy the fun.

Cheers

There is no knife left and I have the same amount of inventory as the walkthrough shows, so where do I find a knife to open the clam?

It's not a knife. Look for a scalloped spoon.