Disgusting ‘rock snot’ fouls Pennsylvania waterways. What is this invasive pest?

An invasive aquatic algae colorfully nicknamed “rock snot” has been found in a Pennsylvania waterway, a state agency says.

Alga didymo Didymosphenia geminata has been found in Quemahoning Creek in Somerset County, says a Facebook post by the Pennsylvania Fish and Boat Commission.

The algae, which gained its nickname from its slimy appearance when wet, poses no hazard to humans but can cause ecological damage by smothering other organisms, PennLive reports.

The Pennsylvania agency warns boaters and fishing enthusiasts to clean their gear to avoid spreading the invasive species to other waterways in the state.

“It takes only one live didymo cell to start a new colony of the alga,” a press release says.

Boaters and anglers should allow exposed equipment to dry for at least 48 hours, the release advises. Thick and dense material, such as life jackets, may take much longer to dry and can also be soaked in hot water containing dishwater detergent.

Rock snot has been discovered in several Pennsylvania rivers since 2007, the release says.