Toxic Finger Sponge

Red-orange fingers standing off a wall, soft to the point of crumbling, and untouched. Nothing grazes this sponge. That is the first thing to notice about it and the reason it matters far beyond this reef.

It defends itself chemically, and the compound responsible - latrunculin - turned out to do something no one expected. It binds actin, the protein that gives every animal cell its skeleton and its ability to move, and it takes that skeleton apart. A cell exposed to it rounds up and stops. Fish that bite the sponge suffer immediately, which is the sponge's business; the laboratory use is ours. Latrunculin from this animal became a standard tool in cell biology worldwide, used any time a researcher needs to switch off the cytoskeleton and see what happens.

The sponge is endemic to the 🌊 Red Sea. A compound in daily use in laboratories across the world comes from an animal that grows on these walls and nowhere else, which is the argument for keeping reefs intact stated in its most concrete form.

Handling it is unwise - the toxin irritates skin, and the sponge is fragile enough that a touch damages it. Photograph, do not touch, and remember what it is.