Ascidians or sea squirts are common in all marine habitats. Some form large colonies as these three photos show. They are vertebrates like us, but actually superficially they look more like sponges! Some of these ascidians also live solitary, they are usually larger than animals that live in the colonies ( look at this photo).
On a dive in Cabilao, Bohol, Philippines I saw a whole coral wall that was covered with one type of blue sea squirts. A beautiful sight! But just a few meter away there were none.
Nikon Coolpix 5000 in sealux housing and subtronic flash
. Copyright Teresa Zubi