The giant mollusc was found in October last year and is still alive and growing, according to Christine Ditlefsen, biologist at the Wadden Sea Centre.
The Pacific oyster (Crassostrea gigas) measures 35.5 cm (13.97 in) in length and 10.7 cm (4.21 in) in width, Guinness said on its website.
Roughly the length of a size 11 shoe, this large mollusc has another five oysters attached to it.
In total, this cluster of oysters weighs 1.62 kg, 'National Public Radio' reported.
Its size and shape could be said to resemble a huge plaintain. But when it was found, the Wadden staff compared the oyster to a large and sturdy shoe, the report said.
"It is 15-20 years old, and probably one of the first Pacific Oysters (Crassostrea gigas) that came to our part of the Wadden Sea," said Ditlefsen.