Aim: The research on the ecology of the rocky coast is now qualitative, quantitative and experimental. The Sri Lankan rocky shore (RS) ecology has not yet been studied extensively in terms of its species diversity to express its truest response to environmental episodes. The present narrative review attempts to reflect the transition of the molluscan diversity of Morawala RS concerning its vertical zonation relative to the Former Repository by Arudpragasam (1984) in his book chapter Ecology of Rocky Shores and Estuaries in Sri Lanka Location: A 500 m stretch of Morawala RS, Negombo, Sri Lanka has been systematically observed for its mollusc diversity and abundance from May 2022 to February 2023 during the lowest low tide time. Methods: The ecological survey was conducted using stratified random quadrate sampling techniques. Shannon Weiner’s diversity index was used to calculate the molluscan species diversity. The present data was then compared with the information in Arudpragasam (1984). Results: 15 different molluscan species representing grazers, gastropods and filter feeders have been identified. The diversity indices for the mid-tide (MT) and low-tide (LT) zones were high during the Northeast (NE) monsoon. However, the high-tide (HT) diversity index was high during the Southwest (SW) monsoon. There was no significant seasonal variation (p>0.05) in the molluscan diversity between the locations within the season and between the two different monsoon seasons. But, molluscan species density was high during the Northeast monsoon season. Conclusion: It was evident similar species richness has been recorded in the present survey similar to the reported species in Ardupragasam (1984). The mollusc species abundance is high in the Northeast monsoon season since the organisms can withstand the dynamics on RS during this period. To predict spatial and temporal variations of the sentinel molluscs in tropical RSs, continuing investigations and observational research are highly warranted.