What accounts for this decline in stromatolite abundance and their restriction to extreme environments?

Garrett (1970) and Awramik (1971) suggested that this decline could be parallel with the rise of metazoans that feed on or bore and burrowed into the stromatolites. 

this theory supports the occurrence of living stromatolites, either in areas with high salt content or salinity levels or in zones with high sediment influx 

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