Confused squirrels

I am fortunate enough to have squirrels visit my garden every day and this morning was no exception. Because we had a severe frost last night and I had forgotten to empty the bird bath, the water was frozen solid when the squirrels arrived hoping to have a drink with their peanuts. They couldn't seem to make out why there was a solid mass where usually there was water.
As I had a few things to do I thought I would go out to deal with their water when they had finished their breakfast as I knew it was more than a five minute task to deal with a frozen bird bath and I didn't want them to have to wait to eat.
After I had done my bits and the squirrels had had their breakfast and left, I went out to deal with the bird bath. I also have a very large tub on the patio with a few pond plants and usually I put a small ball in the middle before the frosts so that it does not freeze over but this year I had forgotten so decided to tackle this as well.
While I was busy defrosting everything I wondered if the squirrels would like an extra treat for Christmas so I decided to put a few proper nuts out on the bird table for them. The birds have not been to my garden since the landlady got some builders to do work on on the gable end wall of the house, digging up the large garden I had grown on the rubble outside my little walled back yard. The squirrels often use the bird table facilities when it rains anyway as they can stay dry while eating their peanuts.
I put out a few hazelnuts and three walnuts onto the bird table and left them. When the squirrels came back later, they had a drink and then when to their nut box which is screwed under the bird table. The first one helped himself to a peanut or three and then got onto the bird table to eat them. He investigated the nuts but I don' think he knew what they were. This was repeated ten minutes or so later by the other squirrel. I left them to it because I was going to pick up my grand-daughter for the week end.
When we came back, it was getting dark so I went out to empty the bird bath so that I didn't have to repeat the defrosting tomorrow. I noticed that the nuts were still there and none were missing. Perhaps these city squirrels have never encountered a walnut tree or hazelnut tree and don't know what they are. Or perhaps they are so used to eating peanuts that have been shelled they don't realise that they are supposed to bite the shells off themselves.