You mean because they are pleated? It is not a problem, just the variety that you are growing. Zapotec is one and Gezhante, Costoluto Genovese and Ficarazzi. They are heirloom tomatoes (older varieties). I think they are usually Greek or Italian varieties. Where did you get your seeds/plants from? They should know if they were giving you an interesting heirloom tomato.
These are the Costoluto Genovese:
