The item left behind in a taxi looked like a typical pouch for a pair of headphones - until it started to move.
"I didn't know what was inside but just screamed and tossed the pouch on the table," said ComfortDelGro customer service officer Gilda Mendoza, who handles items found in cabs.
Inside the grey velvet bag was a baby ball python, which is usually found in Africa.
"Although it was small, it was moving and I thought it would bite me," said Ms Mendoza, 41.
She had found the snake measuring half an arm's length on Monday while logging items at the lost and found department.
The pouch was tucked inside a paper bag that also contained a camera data card and old receipts. Cabby John Ng had found them in the boot of his taxi at 3am on Monday morning.
He said he had not noticed anything unusual when he dropped them off at the lost and found, and could only recall that the passengers who last opened his boot were three Chinese men in their 40s who appeared tipsy.
Yesterday, animal welfare group Animal Concerns Research and Education Society took the snake back to its shelter, which houses creatures rescued from the illegal wildlife trade.
The python, estimated to cost more than $1,000, is believed to have been smuggled into Singapore as an illegal pet.
The Agri-Food and Veterinary Authority said it will be looking into the case. In the last three years, it has dealt with 19 cases of illegal trade or possession of live snakes or their parts.