Florideophyceae, demoted to subclass Floridae in some classification systems, is a class of red algae. It is sometimes merged with the Bangiaceae into the Rhodophyceae, leaving the subclass Florideae in use.
They were once thought to be the only algae to bear pit connection

Pit connection

In Plant anatomy, a pit connection is a hole in the septum between two algal cells, and is found only in the red algae - specifically, all orders except the Porphyridiales and haploid Bangiales. They are often stoppered with "pit plugs". They are in fact neither pits, nor connections, yet the term...

s, but these have since been found in the filamentous stage of the Bangiacae.

"Florideophyceae" is still used by some authorities.

Once thought only to exhibit apical growth, some genera grow by intercalary growth.
Most, but not all, genera have three phases to the life cycle

Biological life cycle

A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

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There are various classification schemes; see Red algae

Red algae

The red algae are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species  of mostly multicellular, marine algae, including many notable seaweeds...

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