Sea cucumber weighing three tonnes and meant to be smuggled to Sri Lanka was seized from Vethalai near here on Tuesday, police said.
Two people were arrested in this connection.
Acting on a tip-off, a team of police and forest personnel seized sea cucumber weighing 3,000 kg and a van used to transport it from a farm in Vethalai near Mandapam.
The value of the seized sea cucumber in the international market was over Rs 1 crore, officials said.
The sea cucumber is classified as endangered species and covered under the Wildlife Protection Act and their harvest prohibited.
The marine species is in demand in Sri Lanka and other South-East Asian countries for use as a delicacy and in preparing medicines.