Blue Buttons clear beach in Puerto Vallarta Mexico OUCH!

After 10 years on this beach, we thought they were the minuscule Jellies that leave no trace after a brief pinprick, but these leave red marks that turn into blisters. Also they were large enough that we could see they washed up on shore. This has never happened before. They were present for about 2 days. Blue little discs dime size or smaller. By the way, the latitude and longitude section of this web page won't allow letters like N or W. That is strange.