It's a neurotoxin and also being researched as a tumor promoter.

Quinault Tribe recalls 29 tons of Dungeness crab due to toxin
by Associated Press
Saturday, January 2nd 2021
SEATTLE (AP) — Nearly 29 tons of Dungeness crab is being voluntarily recalled by the Quinault Tribe.

The recall affects live and uneviscerated Dungeness crab.

The crabs are being recalled due to possible elevated marine toxin levels. The toxin is called domoic acid, which can be harmful to people if the contaminated shellfish are consumed...