Fire Coral
There are two things you need to know about fire corals before you get started. When it comes to the Hydrozoa class, they’re not corals at all—they’re jellyfish-like creatures. It is also important to note that these creatures (which ironically attach themselves on the coral) are capable of inflicting a severe, burning sting that results in an elevated rash.
Stargazer
In order to avoid them, stargazers tend to hide in the sand, making them difficult to spot. There are a few ways to tell if one has stung: bleeding, pain, swelling, and a tingling sensation.