Olympic-sized Oyster

Olympic-sized Oyster

Observation - Olympic-sized Oyster - UK and Ireland. Description: vast brown-capped Oyster-like thing, a foot and a half across, the last picture an older specimen a few metres away with a tennis-ball launcher for scale - thin strip of ground between river Lea and Olympic carpark (stadium in the background of pic 1). Ca

vast brown-capped Oyster-like thing, a foot and a half across, the last picture an older specimen a few metres away with a tennis-ball launcher for scale - thin strip of ground between river Lea and Olympic carpark (stadium in the background of pic 1). Can Oyster grow this large? Some version of Rollrim? Can't be a polypore with those gills.. Growing 2m from an Ash, but it's on a low mound which was constructed a few years ago, a large horseshoe of stacked logs with earth banked over it from behind and on top, enclosing a small meadow area