Mare's eggs
Nostoc pruniforme · Algae
Out of the water · Photo: Maureen Thompson / CC0
Also called Blue green algae balls, Nostoc, Nostoc pruniforme
May produce toxins
Only a lab test shows whether a bloom is toxic. Keep people, pets and livestock out of discolored or scummy water until it is tested.
How to identify Mare's eggs
- Smooth, round, olive to dark green balls from pea size to golf ball size or larger
- Firm, rubbery jelly that holds its shape
- Rests loose on the bottom
- Found in clear, cold water
Similar species
Warty nostoc is lumpy and attached to rocks; bryozoan colonies are attached to sticks and are not green.
Growth profile
| Season | Present year round and grows very slowly over many years. |
|---|---|
| Starts | Cold water |
| Light | Clear water with good light |
| Depth | Loose on the bottom in shallow to moderate depths |
| How it spreads or reproduces | Slow growth and breaking off of new balls |
| Habitat | Cold, clear spring fed ponds, lakes and streams with low nutrients. |
Why it matters in a lake
Rare and indicates very clean, cold water. Often reported as a curiosity.
Where it is found
- Idaho: Rare
- Oregon: Occasional
- Wyoming: Rare
Classification
| Kingdom | Bacteria |
|---|---|
| Phylum | Cyanobacteria |
| Class | Cyanophyceae |
| Order | Nostocales |
| Family | Nostocaceae |
| Scientific name | Nostoc pruniforme |
More colonial cyanobacteria
Gloeotrichia
Star jelly
Rivularia
Warty nostoc
Spirogyra
CladophoraNeed a hand?
Worried about a bloom?
We identify algae under the microscope and test for cyanotoxins, so you know what is in the water and whether it is safe.
Idaho / Wyoming (208) 501-4531Oregon (541) 280-0596