Pyramiding is the result of a few factors. Humidity, diet, exercise, calcium, Vitamin D3 from natural sun are a few factors that when little or none of these are provided, may cause pyramiding. Check that your tort is receiving the proper amount of humidity. Check his diet and avoid foods that contain too much oxalates. Make sure that your tort is out exercising his limbs. And check that he's getting the proper amounts of supplements, along with getting him out for some old fashion sunlight. It would be helpful if you can provide us with a pic of his carapace.