Freshwater eggs?

Freshwater eggs?

Observation - Freshwater eggs? - UK and Ireland. Description: These were brought in to school by a student. Found in a fast flowing stream. Lots were attached to rocks and stones under the water.Are they eggs? or algae?

These were brought in to school by a student. Found in a fast flowing stream. Lots were attached to rocks and stones under the water.Are they eggs? or algae?