Two men were arrested after they were allegedly found in possession of a large amount of perlemoen (abalone) in their vehicle on Tuesday morning, Free State police said.
The perlemoen was valued at around R1m.
Members of the police's K9 Unit allegedly discovered the stash while searching the vehicle near a resort on the N1, between Tierpoort and Bloemfontein, Constable Wendy Nkabi said.
They found about 30 plastic bags of perlemoen hidden under the vehicle's seats and in the boot.
The men, aged 33 and 35, are from Kraaifontein in the Western Cape and were allegedly transporting the perlemoen to Gauteng, said Nkabi.
They are expected to appear in the Bloemfontein Magistrate's Court soon.