Dangerous how? Toxic to humans? At risk of unsettling sand around a rover/human? Is the question asking if they are something that would consciously attack someone?

Everything is dangerous. The key to mitigating that danger is planning ahead for it. A leaf seems harmless, but infection from a cut the leaf gave you could kill you. A marshmallow is fluffy and soft, but if you swallow it without chewing, it could expand and suffocate you.

Asking if something is dangerous is ridiculous. Asking what it is and how to safely handle it is not. The article does a much better job portraying this than the headline does.