Initially, when scientists were first using the taxonomy system to classify living organisms there were only considered to be 2 kingdoms: plants and animals. However, when the microscope was invented, scientists were able to observe differences in organisms at the cellular level! They were also able to observe microscopic living organisms like bacteria that they had not been able to observe before. Scientists realized it was necessary to add 4 new kingdoms to account for the observations they had not seen before the invention of the microscope.
Characteristics of Lancelets:
Small
Elongated
Marine invertebrate
Lacks a jaw
No sense organs
Has a notochord
Example: Lamprey
Characteristics of Tunicates:
Marine invertebrate
Has an outer coat that is rubbery or hard
Has two siphons
Examples: sea squirts, salps
I hope this is the answer that you were looking for.
The coral provides the algae with a protected safe environment (a home) and compounds they need for photosynthesis. The algae in return, produce oxygen and help the coral to remove wastes. Most importantly, zooxanthellae supply the coral with glucose, glycerol, and amino acids, which are the products of photosynthesis.
A virus, because it has a non-cellular structure.
