The 2022 Diadema antillarum die-off event: Comparisons with the 1983-1984 mass mortality.

2021). Disease-driven mass mortality is well known for diadematid sea urchins (Bak et al. 1984;Lessios 1988; Hylkema et al. 2023; ...

https://www.researchgate.net/publication/366893742_The_2022_...

to date, unknown cause.

though I am sure there are a lot among us who blame all the chemical shit we humans dump in the seas