Abstract: An apparatus for grinding specimens, comprises a container, a grinder, a closure for the container, and a seal contained in the closure. The container has an interior grinding surface and contains an opening through which specimens are introduced for grinding. The grinder has a grinding head and an actuator arm extending from the grinding head. The grinding head is adapted to engage the interior grinding surface of the container. Grinding is effected by moving the grinding head against the grinding surface, using the actuator arm. The closure is adapted to close the container and enclose the grinding head therein. The closure contains a passage through which the actuator arm extends when the closure is enclosing the grinding head. The seal is contained in the closure and coaxially aligned with the passage of the closure, such that the actuator arm slidably engages the seal when the arm passes through the closure.