Who would have thought that a stinky, rotten-smelling lump could give you a pot of gold? A couple who happened to stroll along the shore of Middleton Sands beach stumbled upon a highly prized whale vomit.

Gary and Angela Williams were walking on the beach of Middleton Sands near Morecambe Bay in Lancashire when they smelled something stinky like a rotten fish.

The couple followed the smell and found something like the one they saw on a newspaper – an ambergris or whale vomit.

"It was a bit of a shock. It was down a section of the beach where no one really walks," said Gary. "It smells too bad though. It's a very distinctive smell, like a cross between squid and farmyard manure."

They wrapped the waxy rock, which appeared to be bit smaller than a rugby ball, into a scarf and brought it home.

An ambergris is a rock-like whale vomit that comes from the intestinal slurry of sperm whales. This waxy lump is said to protect the whales from sharp and hard materials they eat.

Once expelled, the sticky whale vomit floats over the ocean water years before it will reach a shore. Its exposure to saltwater, heat, and sunlight causes the lump to form into a compact rock. It is rare because of the time it takes to harden and the small chance it would be found by lucky beachgoers.

A whale vomit is said to be "floating gold" because of its high value and rareness. It also attracts many perfume manufacturers as the substance is said to develop a sweet, earthly scent.

Gary, an engineer, weighed the newly found ambergris onto a scale, revealing 1.57 kilograms (3.4 pounds) of stench – or approximately £50,000 ($70,000) worth of money.

The couple is now talking to some potential buyers of the whale vomit. In the meantime, they kept the sought after ambergris in a safe storage while they are consulting experts from New Zealand and France.

In 2013, a 2.7-kilogram (5.9-pound) whale vomit also discovered near Morecambe Bay was valued at £120,000 (more than $170,000).

Last September 2015, a 1.1-kilogram (2.4-pound) lump found on one of Anglesey's beaches in Wales was sold for £11,000 (over $15,000) in an auction at Macclesfield, Cheshire.

"If it is worth a lot of money it will go a long way towards buying us a static caravan, it would be a dream come true," Gary said.

Photo: Day Donaldson | Flickr