a An individual cassiosome poised in a 100-μm mesh opening, revealing the irregular ‘popcorn’ shape of the cassiosome bearing numerous cilia (pink arrows) protruding from the peripheral layer. White rectangles correspond to magnified region shown in (b) and (c). b, c Close up of the cassiosome reveals cilia (pink arrows), and thicker tubules (white arrows) of discharged O-isorhiza nematocyst capsules (blue arrows) in the periphery which is lined with collapsed nematocytes (cyan arrows). Spiny nematocyst tubules (white arrows) are outnumbered by the abundant cilia (thinner filaments) (pink arrows). d Depressions fringed by deflated cell membranes outlining nematocytes (cyan arrows in c and d) following deployment of O-isorhiza nematocysts (blue arrows in c) along the cassiosome surface. e A different cassiosome from that in (a–d). All cellular components were lost (possibly in dehydration stage of methods) but for discharged O-isorhiza nematocyst capsules (blue arrows) and corresponding spiny tubules (white arrows) in the cassiosome periphery lined with collapsed nematocytes (cyan arrows). White rectangle corresponds to magnified region shown in (f) revealing the dense central, fibrous extra-cellular matrix (green arrow). Unidentified microscopic particles also present (orange arrows). Scale bars as indicated in SEM images.