A specimen carrier (100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100) configured to house and store specimens for cryopreservation, the specimen carrier comprising: an elongate member (102, 302, 402, 502, 902, 1002) defining an external sealing surface (116, 316, 416, 516, 916, 1016) and a support surface (120, 320, 420, 520) upon which a specimen can be carried, the elongate member made of a first material having a first coefficient of thermal expansion; and a cap (104, 204, 604, 704, 804, 904, 1004) having a region configured to surround a specimen, wherein the cap is configured to be passed over a portion of the elongate member in an ambient environment of a first temperature to close the region of the cap that surrounds the specimen when the cap is passed over the portion of the elongate member, the cap defining an internal sealing surface (128, 228, 628, 828, 928, 1028) formed complementary to the external sealing surface defined by the elongate member, the elongate member and the cap being configured such that, at the first temperature, an interface formed between the external and internal sealing surfaces comprises an interference fit, and the cap being made of a second material having a second coefficient of thermal expansion that is greater than the first coefficient of thermal expansion, such that when the portion of the elongate member is covered with the cap and the portion of the elongate member and the cap are together placed in a cooling substance of a second temperature that is lower than the first temperature, the cap contracts to a greater extent per degree temperature change than does the elongate member causing the internal sealing surface of the cap to compress the external sealing surface of the elongate member and increase tightness of the interference fit at the interface (132, 232, 670, 672, 770, 771, 772, 773, 870, 970, 1070, 1170) between the external and internal sealing surfaces to form a hermetic seal along the interface. an elongate member (102, 302, 402, 502, 902, 1002) defining an external sealing surface (116, 316, 416, 516, 916, 1016) and a support surface (120, 320, 420, 520) upon which a specimen can be carried, the elongate member made of a first material having a first coefficient of thermal expansion; and a cap (104, 204, 604, 704, 804, 904, 1004) having a region configured to surround a specimen, wherein the cap is configured to be passed over a portion of the elongate member in an ambient environment of a first temperature to close the region of the cap that surrounds the specimen when the cap is passed over the portion of the elongate member, the cap defining an internal sealing surface (128, 228, 628, 828, 928, 1028) formed complementary to the external sealing surface defined by the elongate member, the elongate member and the cap being configured such that, at the first temperature, an interface formed between the external and internal sealing surfaces comprises an interference fit, and the cap being made of a second material having a second coefficient of thermal expansion that is greater than the first coefficient of thermal expansion, such that when the portion of the elongate member is covered with the cap and the portion of the elongate member and the cap are together placed in a cooling substance of a second temperature that is lower than the first temperature, the cap contracts to a greater extent per degree temperature change than does the elongate member causing the internal sealing surface of the cap to compress the external sealing surface of the elongate member and increase tightness of the interference fit at the interface (132, 232, 670, 672, 770, 771, 772, 773, 870, 970, 1070, 1170) between the external and internal sealing surfaces to form a hermetic seal along the interface.