Green fleece, washed up on a Rhode Island beach.
Green fleece, washed up on a Rhode Island beach.
E. Zabel, courtesy of URI

Green Seaweed
Green Fleece (Codium fragile), Hollow Green Weed (Enteromorpha intestinalis)

Alternate common name for Codium: Dead Man's Fingers.
Alternate common name for Enteromorpha: Enteromorpha.
Appearance: Green fleece is a dark green seaweed, tubular and fingerlike; grows in clumps, often attached to rocks. Hollow green weed is a pale green seaweed, hollow and branched; found alone or in clumps.
Habitat: Both are found in salt marshes, open water, tide pools, and rocky shores attached to rocks, shells, and other algae. Green fleece is more common in higher salinities. Hollow green weed is common in brackish and low-salinity waters.
Seasonal appearance: All year.


Green fleece is a tubular seaweed, dark green to yellow in color, with a thick, spongy texture. It can grow up to 3 feet long, with branches up to 1/2 inch in diameter. The coarse, bushy branches grow in Y-shaped forks resembling green fingers or a mass of worms. When clustered, green fleece often looks like a shapeless carpet-like mat. Green fleece is often found washed up by the tide in ropy masses, and when dried by the sun, it can become white or gray in appearance.

Hollow green weed is pale green or yellow in color, tubular and branched. The branches are about 1/4 inch in diameter, and up to 10 inches long. Sometimes called by its Latin name, Enteromorpha, hollow green weed is named for its tubular shape.

Life History and Growth

Green seaweed, or green algae, consists of many diverse species. Although most predominant in fresh water, green seaweeds have many marine representatives, including green fleece, hollow green weed, and sea lettuce. Both green fleece and hollow green weed use holdfasts to attach to a wide range of objects, from rocks to living shellfish, shells, and other algae. Hollow green weed tolerates a wide range of salinities, and can be found in nearly fresh water to very salty water.

Critter Fact Green fleece was introduced to North America from Europe around 1957, most likely attached to the bottom of ships.
Hollow green weed, attached to a rock on the Rhode Island shore.
Hollow green weed, attached to a rock on the Rhode Island shore.
E. Zabel, courtesy of URI

Special Notes

Adapted from The Uncommon Guide to Common Life on Narragansett Bay. Save The Bay, 1998.