They have their unique colour science! :)
Incredible research in the link you provided, but I am nowhere near scientific enough (or silly enough to pretend to be) to understand the level of detail - looking for the post-death biomarkers in the limestone offers an incredible insight.
Everything leaves its mark, we just have to look closely to find it.
A local guy has written about the algae bloom in pretty plain language. Helps to understand what is going on.