Looking prehistoric, lengthy, and deeply strange, a 20-foot long basking shark was accidentally caught by a trawler this week off the town of Portland, in southwestern Australia.

The shark is the second-largest living fish in the world, after the whale shark. Mild-mannered, it is one of three plankton-eating sharks besides the whale shark and megamouth shark.

Basking sharks are not common fish off Australia, and the last one was caught off the country in the 1930s, according to National Geographic.

The shark was dead when it landed on the deck. The fishermen who caught it have donated it to Museum Victoria, to be preserved for science. Scientists from the Melbourne-located museum traveled to Portland to dissect the specimen, which was too large to transport in one piece, as reported by the Australian Broadcasting Corporation.

Museum Victoria's biobank also took tissue and skin samples, which will be available for DNA and isotope analysis that could reveal where the shark lived and what it ate, said Victoria's daily newspaper The Age.  

The scientists collected eight vertebrae, the fins and tail fin and the head with its jaws and teeth. One plan includes making a mold from the head and fins, for display, reported The Age. 

"This is a great acquisition for the museum," said Martin Gomon, senior curator of ichthyology at the museum, according to The Age. "It's wonderful to be able to get some information about a shark we don't come across that often."

Basking sharks are caught somewhat regularly by fisherman off New Zealand, and seem most common in the North Atlantic, around the UK and the U.S. East Coast, according to National Geographic.

The National Oceanic and Atmospheric Administration (NOAA) lists the sharks as a "species of concern," and Canada classifies them as endangered, since their population seems to have declined over past decades. They are targeted illegally by fishermen for their large fins, which can be sold lucratively in the shark-fin soup trade.