David A. McKayA good case-study of shifting baseline syndrome - much of Europe was once surrounded by oyster reefs as large and complex as tropical coral reefs, now largely forgotten:
https://www.theguardian.com/environment/2024/oct/03/europe-oyster-reefs-study
Props to the team who catalogued records of them in this fascinating (but tragic) paper: https://www.nature.com/articles/s41893-024-01441-4