BOSTON — An invasive species known as “sea squirts” has spread on the sea floor off New England, but scientists say it’s not all bad news.

The species of this soft-bodied animal spreads rapidly across the ocean bottom in rope-like chains or mats. It was discovered offshore in Georges Bank in the early 2000s, and has been found over about 180 square miles there.

The sea squirts’ spread raised concerns about effects on valuable species that live on or near the sea floor, such as scallops and cod. Those effects are still unclear, but scientists have found it can be beneficial for some species, including winter flounder. That fish benefits because the sea squirts provide a good habitat for worms that the flounder likes to eat.

Scientists say more study is needed to determine the sea squirts’ long-term effects.