Police conducting a routine inspection of a frozen seafood shop in eastern Spain have netted 13 Roman amphoras and an 18th-century metal anchor, all of which were apparently found by the owner’s son on fishing trips and used to decorate the premises.

After stopping in at the shop in the coastal town of Santa Pola, in Alicante province, officers from the Guardia Civil’s environmental department noticed rather more than squid, hake and cod on display.

“They saw various ceramic amphoras dotted about the place, a metal anchor and an engraved limestone plaque – all of which, at first glance, appeared to be of some considerable age,” the force said in a statement.

According to local media reports, the shop-owner’s son had come across the items while out fishing and had brought them back to deck out his father’s business.

The items were confiscated and the Valencian regional government’s culture department notified. After a preliminary examination suggested the ceramic vessels were Roman and could date from the first century AD, the amphoras were taken to the Santa Pola Museum of the Sea.

Experts at the museum concluded that the jars probably came from shipwrecks off the Mediterranean coast and were protected by archaeological heritage laws. The anchor was dated to the 18th century, while the plaque was engraved with the word “ESTE”, or east.

“Most of the 13 amphoras would have been used to store and transport oil that was produced in Andalucía and shipped to Rome from Portus Ilicitanus – or what is now the port of Santa Pola,” the statement added.

“Others would have been used as containers for wine or fish sauce.”

The force said proceedings had been brought against the shop-owner and his son on suspicion of offences against historic heritage and knowingly buying or possessing objects of dubious or illicit origin.