According to Nguyen Thanh Son, chairman of the Nha Trang Ward People's Committee, on October 4 that local authorities had received reports of the creatures along the beach.
The sea urchins are about half the size of a rambutan, with white bodies marked by brown stripes and covered in stiff, sharp spines.
Son said they had been identified as sand sea urchins and could cause itching and pain if accidentally stepped on.
Their appearance in Nha Trang waters is not unprecedented, with similar occurrences recorded in 2014 and 2019.
Local authorities and the Nha Trang Bay Management Board collected and disposed of the sea urchins that had washed ashore to ensure the safety of residents and tourists.
Authorities advised anyone who steps on a sea urchin and develops unusual symptoms to seek medical attention.