Memory Stone

Memory stones were originally a black gemstone with no actual abilities, however each of them had a certain ability to absorb spiritual energy and transfer into tools which could be used for recording, tools that could be used as keys or even storage tools.

A low grade memory stone was one which had managed to take in a slight amount of spiritual energy and changed into a stone which could perhaps record one Martial or Spiritual Art Skill, it could record a real action for a short time and keep that one action or it could be used to send one message to another person.

Due to the lack of Spiritual Energy it was usually used as a container of Martial and Spiritual Art Skills. The memory stone would shatter when the Spiritual Energy ran out, and that would usually happen if the stone had been used a few times. This did not matter whether it was a Martial or Spiritual Art Skill, a recording of a fight or even a message to a friend.

Mist
If the memory stone had contained a skill created by a lower dantian ranked expert, then it would be filled with black mist which was almost impossible to see. If it contained a skill created by a middle dantian ranked expert, the mist would be grey, and if it was a higher dantian ranked expert, the mist would be white.