coral commonly known as polyps are commonly distributed around Indian and pacific ocean. learn it's general characteristics types along with easy examples. if you want me to add economic importance let me know in the comment box.

1. CORALS
GENERAL FEATURES & TYPES

2. GENERAL
FEATURES
– Corals commonly called as Polyps are marine animals of a
great economic importance.
– It belongs to Class= Anthozoa (mainly) and Hydrozoa ( few)
– Solitary or colonial animals
– They secrete a hard structure of exoskeleton made up of
calcium carbonate called as CORALLITE/CORALLUM.
– Mainly categorised under 3 groups.

3. 1.Hydrozoans
 Comes from Order = Hydrocorallina
 Sub-orders = Milleporina (e.g. Millepora)
Stylasternia (e.g. Stylester)
 It has modified epidermis called as calcioblastic layer
which secretes massive exoskeleton made up of calcium
carbonate.
 Found in coral reefs.

4. 2.Hexacorallina
 Order = Madreporaria (e.g. Madrepora)
 These are stony corals or true corals.
 Known as principle builders of coral reefs.
 Either solitary or colonial.
 Secretes both Corallium and corallite
 Polyps have different shapes made up of hard
calcareous skeleton.

5. 3.Octocorallians
 Dead man’s finger (Alcyonium) is a marine, soft and
colonial coral. Calcareous spicules are present
comprises of endoskeleton embedded in coenchyme.
 Organ pipe coral (Tubipora) made up of misogleal
calcareous spicules. These spicules form parallel and
vertical tubes. Skeleton has red colour due to the
presence of iron salts.
 Blue corals (Heliopora) has massive calcareous
Corallium secreted by polyps.