Yellow urchin extract

Yellow urchin extract was a type of poison deliverable via water inhalation, making it effective underwater. It was harvested by aquatic humanoids to use against their foes from a certain species of the urchin.

Description
Yellow urchin poison (the extract) was most valued among aquatic sentient species for its ability to be delivered via inhalation unlike other types of poisons. When extracted, it was a thick and milky fluid. Used underwater, it created a cloud of poison wide that naturally dispersed after 10 minutes, or 1 minute in strong current. The toxins affected any water-breathing creatures that passed through the poison cloud (including creatures under the effect of the water breathing or a similar spell), unless they were able to hold their breath. A vial of this unique poison was valued at 800 gp, owing to harvesting being a long and tedious process.