Train a Digimon with Earth element. If it is a Virus, kill only data digimon. If Vaccine, kill viruses. And if your earth digimon is a data type, then just return all kind of eggs to the scanning NPCs with the Digimon at your side. When you'll get the message: Earth aTTRIBUT 100%, open the Digimon window ("D") and in the "attributs" section click on the earth icone. It will reset the bonus damge of your digimon, but you'll get the earth ttribute crystal data.