Extreme temperature shifts and excessively dry climates are the biggest threats to your natural fidget. Because they are organic materials, sudden environmental changes can cause the shells to crack.
To protect your pieces, always store them in a sealed zip-lock bag or a display case when not in use, especially during harsh winters or in heavily air-conditioned rooms. Avoid sudden exposure to freezing winds or direct tropical sunlight. Protect them well, and they will remain your reliable somatic anchor for decades.