I feel a bit of a fraud writing Baby Play as T now toddles everywhere and is very much a little toddler but this is a great activity for non-toddling just over 1 year old and younger. It helps to improve the pincer and fine motor skills as well has hand transfer, it's also great for sensory exploration as shells have interesting texture - we only used one sort of shell in the play which had a rough and smooth side but you could combine different shells to introduce different elements to the play as well.
Shells are very new to T - I hate to admit this but because our local beaches don't tend to have a lot of shells on and the fact that I haven't collected any since I was a child I had to go and buy some shells for J and T to play with (on our to do list this summer is to start a shell collection). So one of the first things I did was let her explore them - now you will notice that she is in her high chair, the reason, because I have been giving her the shells whilst J does some craft that I feel wouldn't be good for her to join in with like using Acrylic Paints or we have friends over.
Typical T one of the first things that she did was bang the shells together to try and get a noise out of them - she found that it didn't work but at the same time did discover that one side was rough and the other smooth and spent ages turning them over and over feeling them.
I then set up a little activity with her the next time that we did some crafts with two bowls and her shell in one of them - we had done something similar with pasta before but this time with the added element of the different textures it was interesting to see her approach it differently - as she picked up each shell she would feel the shell, then lay it rough surface down in the next bowl.
I've been reading some books about the Montessori method and one of the things that I have noticed that they talk a lot about is the left to right transfer so I've made sure that it's always the bowl on the left that has the shells in - the importance of this is because of the way that we read from left to right so it's get children used to looking from the left to the right.