drusa bedeutet auf Englisch

geode [geodes]▼(hollow stone with crystals on the inside wall)
noun
[UK: dʒˈiːəʊd] [US: dʒˈiːoʊd]

shell [shells]▼(accreted mineral formed around a hollow geode)
noun
[UK: ʃel] [US: ˈʃel]