One of the world’s largest living animals washed up ashore at Crissy Field this past Wednesday, captivating passersby — and sparking up curiosity about how the marine mammal died. Now four days and one necropsy later, it's still unclear as to how the whale perished.

At lengths of up to 49 feet long and tipping the scales north of 60,000 pounds, gray whales are immense creatures that demand attention... especially when they appear on solid ground. This past Wednesday, a 41-foot mature female was found "moderately decomposed" along the shoreline at Crissy Field.

After it was initially found by police, the body was swiftly towed to Angel Island State Park where a joint team of scientists from the California Academy of Sciences and the Marine Mammal Center in Sausalito descended to perform an impromptu necropsy.

The confirmed cause of death? TBD.

Per KTVU, Marine Mammal Center official noted that the whale was altogether healthy; the female showed no signs of underlying illnesses or evidence of blunt force trauma that may have been caused by a boat.

But what the team does consider true is that the once-endangered animal died suddenly.

"We're concerned to discover this year's first gray whale death here in the San Francisco Bay Area because this species already faces many environmental challenges," Marine Mammal Center Necropsy Manager Barbie Halaska said in a statement, per the news outlet. "While this whale's death is a sad loss for the population, the information gathered from these whales is shared directly with our partners, helping inform policy decisions that can protect habitat areas, change shipping lane speeds that intersect migration routes, and better understand shifting food sources for marine mammals."

Like humpback and blue whales, gray whales are especially prone to fatal crashes with large vessels. (It's that reason alone why the past two Dungeness Crab fishing seasons were postponed: to safeguard migratory whales and other marine life traveling along the Pacific coastline.)

Over the past few decades, whales consuming single-use plastic products has resulted in dozens (if not hundreds) of recorded deaths. This is particularly true with sperm whales which often mistake large floating trash bags for squid, a common food source for the behemoths.

Climate change, too, has played a part in whale deaths.

Warming oceans have caused schools of plankton — the main food source of gray whales — is driving plankton blooms down and toward the poles,  forcing whales that feast on them to travel further, at times dangerously close to human activity, in order to survive.

"As gray whale migration season continues along the Pacific Coast, adult female gray whales and their calves are the last to migrate northward to their feeding grounds in the Arctic," Marine Mammal Center Director of Pathology Dr. Padriag Duignan said to KTVU. "Following the huge increase in gray whale deaths, it was encouraging to see this particular whale in good body condition after examining so many that suffered from malnutrition."

Marine mammal center experts plan to take a second look at the whale; the second necropsy will primarily be done to examine skeletal remains; this will either prove or disprove that human activity is not to blame for the whale's death.

Related: Dead Gray Whale Washes Up at Crissy Field, Gets Towed to Angel Island for Necropsy

Commercial Dungeness Crab Season Will Start December 23 — After Whales Have Migrated to Breeding Grounds

Image: Gray Whale calf leaves mom and swims up to an inflatable boat full of tourists (Photo: Getty Images/Christhilf)