Xylok spacecraft

In the distant past a Xylok spacecraft crashed into the Earth, trapping the Xyloks in the crust of the planet. When the volcano Krakatoa erupted, one crystal escaped. Centuries later, Sarah Jane Smith retrieved the living crystal, took it to her home on 13 Bannerman Road, and found it could communicate with her via her laptop. The crystal informed her how to build the computer to house the living crystal, becoming Mr Smith. (TV: The Lost Boy)