Hannah Foster discovered thousands of the marine invertebrates at Wardie Bay before going for a swim at 08:00 on Thursday.
She told BBC Scotland News she was “shocked” to make the discovery.
“It was really sad and bizarre to see them all washed up and tangled in the seaweed, there were so many,” she said.
“It was so cold last night that half of them were all frozen and dead.
“We did a short swim and took some with us that looked like they still had colour in a bid to save them, I don’t know if it would have done anything but you always have to try in these situations.
“A local who has lived near the bay for the last five years said this has only happened once before, it is not a normal sight,” the 27-year-old said.