The Krulius had several data-pods, each one contained one alien lifeform. The data-pods stored the alien lifeforms in quasi-digital suspension.
The alien lifeforms were taking from specific locations in the galaxy. Within the Krulius collection were a Sontaran, a Bane, a Raxacoricofallapatorian and a Graske.
The data pods were on a space ship, which hit an asteroid and was going to crash Earth. The Krulius safed the aliens within the data-pods by uploading their digital bio-data into the world wide web, using a digital bio-converter. The aliens were later tracked down by Mr Smith, Rani Chandra and Clyde Langer and released. (COMIC: Monster Hunt) When the Judoon caught the Krulius all his captured aliens at Doloth Star Base were set free. However the Krulius had managed to take clone cell samples of his former captured aliens with him, which allowed him to grew perfect copies of these aliens. Several copies of this aliens he kept in the data-pods of his spaceship. (COMIC: Return of the Krulius)