The eggs of marine organisms are often washed up on beaches. Although the strandline shell assemblage at Ishikari Bay, Japan, is known to include several gastropods with remarkable egg morphology, only one of these species is known as the “beach-cast” egg. In this study, I searched for and collected beach-cast gastropod eggs by walking along Zenibako Beach in Ishikari Bay every month from November 2022 to January 2024. I observed the egg masses of eleven species from four families, all of which exist as beach-cast shells. The occurrence and abundance of egg masses varied considerably among months. There was a general pattern in the seasonal variation of egg abundance among species, mainly related to the parent’s reproductive phenology. In naticid egg masses（free-demersal, relatively fragile） , there was a peak of abundance during their egg-laying season and it disappeared during their non-breeding season. The egg capsules of buccinid, columbellid, and muricid whelks（sessile, relatively durable）were absent or scarce during their egg-laying season, reaching highest abundance after their hatching season（within two months） and then gradually declining in abundance, although some may remain for the following breeding season. Gastropod eggs were a common find on the beach at the study site.

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Additional description was done based on the information obtained later about drift seeds of three Omphalea species that the author had recorded in Japan. The drift seeds of O. diandra have been misidentified; their correct name is O. sargentii. The morphology of the drift seeds of O. bracteata was described in detail based on the observation of many specimens. Since the first record in 2011 drift seeds of O. papuana have been recorded on several coasts in southwestern Japan. The distribution map of the drift sites was shown.

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2025年2月に鹿児島県大島郡徳之島の海岸に打ち上げられたウニ類の乾燥裸殻標本を，その形態的特徴から不正形ウニ類 Sinaechinocyamus mai と同定した．本報告は，本種の日本からの標本に基づく初記録であり，種の北限記録となる．本種の新称和名として「ナミダノシズクカシパン」を提唱した．

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The drift endocarps of Canarium ovatum and C. album（Burseraceae）were newly recorded in Japan. The size and shape of them was clarified. A total of four species of Canarium endocarps have drifted on the shores of Japan.

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