Common name: Hydrozoans

Hydrozoa is a class within the phylum Cnidaria, consisting of a diverse group of mostly marine organisms. Members of this class are known for their life cycles, which can alternate between polyp and medusa stages. Hydrozoans include species like the infamous Portuguese man o' war and various types of hydroids. They can form both solitary and colonial individuals, with some creating intricate, plant-like structures. In reef aquariums, certain hydrozoans can be both fascinating additions and pests, depending on the species. Hobbyists should be aware of their potential to sting both humans and other tank inhabitants.

1. 
   Common name: Violet Lace Coral

   Scientific name: Distichopora violacea
2. 
   Common name: fire coral

   Scientific name: Millepora alcicornis
3. 
   Common name: bladed fire coral

   Scientific name: Millepora complanata
4. 
   Common name: Rose Lace Coral

   Scientific name: Stylaster roseus