What is this monster?

[TwoTankAmin58]

I was not even sure what plant you meant. The one I thought you meant was the taller one with the long leaves which I believe is one of the long leaf Hygrophilias.

Long leaf Hygrophila typically refers to fast-growing, hardy stem plants like Hygrophila angustifolia (Willow Hygro) or Hygrophila corymbosa (Temple Plant), popular for aquarium backgrounds. They feature long, narrow to broad bright green leaves and, under high light and nutrient-rich conditions, can grow up to 20 inches

 

[SammyTargo]

Looks like a Pogostemon. I don’t have this exact species but looks very similar.

Upon my brief research, I think it is a Pogostemon Stellatus. Some people call it Pogostemon Octopus

 

[Munroco]

The full name is pogostemon stellatus octopus - PSO.

The full name is pogostemon stellatus. There is a variation commonly known as octopus. Looks like a deformed version of stellatus. Not so attractive IMO.

 

[anewbie]

The full name is pogostemon stellatus. There is a variation commonly known as octopus. Looks like a deformed version of stellatus. Not so attractive IMO.

I suppose but in practicality it is difficult to find just plain pogostemon stellatus at least in usa. Some of the colour variants are available though they are much harder to grow.

 

[Munroco]

I suppose but in practicality it is difficult to find just plain pogostemon stellatus at least in usa. Some of the colour variants are available though they are much harder to grow.

I'm not sure if it is hard to find in the UK, probably not, but I know I have given away or thrown out masses of it over the years.
I probably started with 5 or 6 stems and have never purchased any more. It grows very quickly and within a couple of weeks you can be cutting the stems in half and replanting them.