Jitsukar was a brown paste refined from the venom of the jitsukar, a large clam native to cool freshwater lakes, closely related to the jitsu and jitsutyr, despised as a dangerous pest by fishermen. Jitsukar was prepared by immersing the clams in cold salt water, inducing them to secrete the oily venom as a protective measure. Some of the oil floated to the surface, where it was collected and mixed with flowers of sulfur and finely ground charcoal to form the sticky paste. Jitsukar killed by destroying the victim's lungs; at minimum, it had no ill effects.