Noah's Keyhole Limpet

Puncturella noachina is a small marine gastropod in the family Fissurellidae, distinguished by a conical, ribbed shell perforated near its apex by a keyhole-shaped opening used to expel respiratory and waste products. Like other keyhole limpets, it is a grazer, using its radula to scrape algae, biofilm, and encrusting organisms from hard substrates. In doing so it contributes to the turnover of microalgal films on rocky surfaces and serves as a prey item for small predators within benthic marine communities.

The species has an unusually wide, cold-water-associated distribution, recorded from the North Atlantic, Arctic, and Southern Ocean regions, including Norway, Iceland, Greenland, Svalbard, the United Kingdom, Canada, and the United States, as well as more scattered occurrences reported from South America, the southern Indo-Pacific, and sub-Antarctic islands. It inhabits hard marine substrates, typically attaching to rock and shell surfaces in subtidal to deeper shelf waters.

No reliable population figures are available, and the population trend is currently listed as unknown. The species faces a combination of ongoing pressures: ocean acidification, which can weaken calcium carbonate shell structures; rising sea temperatures; coastal development and associated habitat degradation; marine pollution; and localized overharvesting by shell collectors.

Specific, targeted conservation programs for this species have not been widely documented; measures affecting it are largely indirect, arising from broader marine protected area networks, water quality regulations, and international efforts to curb greenhouse gas emissions and ocean acidification. Given the combination of multiple compounding stressors and the absence of population monitoring data, the species' conservation trajectory remains uncertain, and its current Endangered classification reflects significant concern despite limited quantitative data.