SALT LAKE CITY, Utah (AP) — Tiny shrimp eggs have been showing in such huge numbers in Utah’s Great Salt Lake that some parts of the water looked covered with an oil slick.

Cold weather in fall or winter causes the lake’s small brine shrimp to produce the eggs, or cysts.

When conditions are right such as this year, the eggs come together in giant masses.

The cold temperatures of fall/winter cause brine shrimp to produce dormant cysts. Once the weather warms back up and conditions improve, these cysts will hatch as nauplii and continue their life cycle. #GreatSaltLakeStatePark #UtahStateParks #GreatSaltLake #BrineShrimp #lakelife pic.twitter.com/ZBhaBsy1sO

— Great Salt Lake USP (@GreatSaltLakeSP) December 4, 2020

Photos from the Great Salt Lake State Park and Marina west of Salt Lake City show what looks like a swirling, brown slick on the water.

When the weather warms the eggs are expected to hatch and continue their life cycle.