Venus has a few weird domes that seem to be different from the rest of its surface, which may be because they are full of crystals formed from cooling magma
Source:
https://www.newscientist.com/article/2221118-strange-volcanic-domes-on-venus-may-be-made-from-hot-crystal-mush/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home