In the coastal town of Seaside, Oregon, an unusual sight greeted residents as thousands of sea cucumbers washed ashore. This rare phenomenon occurred due to a combination of rough surf and an exceptionally low tide.

These sea cucumbers, known as skin-breathing sea cucumbers, are characterized by their partially translucent, pinkish gelatinous bodies. Typically, they reside buried in the sand near the low tideline and further out into the sea.

However, on Tuesday, these creatures were found scattered over a stretch of more than two miles along Seaside Beach, according to Tiffany Boothe, assistant manager at the Seaside Aquarium.

“The tideline is literally covered with them,” Boothe remarked. Although these sea cucumbers generally measure about half an inch in length, they have the potential to grow to around six inches.

“They are literally littering the tideline,” Boothe said. They’re about a half-inch long but can grow to about 6 inches.

The phenomenon can occur whenever surf and tide conditions coincide, which can mean a few times a year or once in a few years.

Sometimes a few will be scattered here and there on the shore but there were large groupings on the beach during this latest episode.

Boothe hasn’t seen this many on the beach in a couple of years.

The sea cucumbers aren’t capable of returning to their natural habitat on their own so they will dry up and die, Boothe said.

They’ll provide nutrients for the beach hoppers, beach fleas and other invertebrates living along the tideline that will feast on them. Birds don’t eat them.

Whatever remains will likely dry up quickly and blend in with the sand.

Booth suspects they’ll be gone by Wednesday or Thursday.

The scientific name for the cucumbers is Leptosynapta clarki. They live along the coast from northern California to the Gulf of Alaska.

Seaside is about 80 miles northwest of Portland, Oregon.