What nickname was given to the small, spherical mineral grains found by Opportunity that typically form in wet sediments?

Answer

"Blueberries"

Small, spherical mineral grains nicknamed 'blueberries' were identified. These spherules contain gray hematite and characteristically form when minerals concreate within sediments that were once wet.

What nickname was given to the small, spherical mineral grains found by Opportunity that typically form in wet sediments?
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