One low tide last January, Don Parsons' clam fork hit something hard in the soft mud of a clam flat off of the Annisquam River that re-opened in the winter.

The object turned out to be an intact, but dead, bivalve mollusk. The shells, about four inches in diameter, had a scallop shape, but an oyster's thick, rough, and layered texture.

"This is like an oyster that turned scallop. I've never seen a creature like this before, and I've been clamming commercially for 40 years," said the 53-year-old West Gloucester resident. "This creature was in with the clams about eight inches beneath the surface and had probably been dead for about two weeks. A large sea worm was feeding on its insides. The worm most likely went inside after the animal had died.

"I've occasionally dug up a stray sea clam in the mud flats while (soft shell) clamming. Oysters (ostrea virginica) are fairly common along the rocky areas,'' Parsons added. "They have always been here, and they go in cycles like the clams."

Sea scallops live further off in Ipswich Bay, especially on sandy bottoms with swift currents.

Fortunately, Parsons brought the mollusk home where he cleaned out the insides, rinsed the shells off and set them on a windowsill to dry.

"The sun bleached the shells. They were originally a light tan," he said.

Several close-up photos of the shells were e-mailed to Dr. Roxanna Smolowitz, the lab animal veterinarian and aquatic veterinary pathologist at Woods Hole Marine Biological Laboratory, and to Bill Walton, an agent for the County of Barnstable Cape Cod Cooperative Extension, for an identification.

Parsons received some answers a couple of weeks ago.

"After some evaluation, we think this is an example of Ostrea edulis | the European oyster," Walton said.

East Coast Shellfish Growers Association literature states, "The species was introduced in New England states by researchers in Milford Labs around the turn of the (20th) century. Wild populations became established in isolated areas in Connecticut, Rhode Island, Maine and Atlantic Canada. The European oyster has a unique flavor that's very metallic | sort of like sucking on pocket change."

The identification was surprising, but not shocking.

"We were surprised to hear about this oyster, but not flabbergasted,'' Walton said. "I'd expect to see one around here (on Cape Ann), but not very often. A mud flat is not a natural habitat for an oyster. That's a sub-tidal species (like the scallop) that lives on and not in the bottom," Walton added. "It was kind of a funny place for an oyster."

How this oyster got to that sheltered mud flat, and especially eight inches down, still remains a mystery.

Coddock update

Meanwhile, the Terminator's "coddock," featured in the Times on March 20, relocated to Washington, D.C., last week. The vessel's crew | owner and operator Paul Theriault of Rockport and crewman Joe Roderick of Gloucester | should also be getting some answers soon on their fish.

The Times' "coddock" story got the word out about this catch to the scientific community. Dr. Bruce B. Collette from the Smithsonian's National Museum of Natural History forwarded this request to Ebb & Flow: "If we could get DNA-testable tissue along with the fish, we could really find out if it is indeed a hybrid."

Dr. Collette is also co-editor of the third edition of Bigelow & Schroeder's "Fishes of the Gulf of Maine," which came out in 2002. The frozen fish was specially shipped to Dr. Collette early last week.

"I'll let you know when we have some data on its parentage," he reported.