Majano anemone
A short, thick-columned pest anemone with stubby tentacles, usually vivid green or with pink-tipped bulbs under actinic light. It stings neighbouring corals like Aiptasia does and spreads the same two ways — by splitting, and by leaving fragments of its foot behind as it moves.
Make sure that's what it is
Short, crowded tentacles with clubbed or bulbous rounded tips, on a squat muscular column, often fluorescing bright green. Aiptasia by contrast is long, thin, clear and needle-tipped. Getting this call right matters less than it sounds — the removal methods are near-identical — but the two spread at different speeds and majano is the more stubborn.
What it looks like
No photos of Majano anemone yet. If you have it in your tank, a clear shot here is what the next person will compare theirs against — it's the most useful thing you can add to this page.
Getting rid of it
In the order we'd try them. Every method cites where it comes from, and where the reason a treatment works isn't actually established, it says so.
Inject it, or take the rock out
ChemicalWhy it works
Majano spreads by longitudinal fission and by pedal laceration — it splits, and it leaves behind microscopic clusters of cells as it moves across rock, each of which can become a new anemone. Documented reports put five to ten new anemones behind a single botched removal. So the same rule as Aiptasia applies and applies harder: destroy it in place, or take the whole rock out and work on it in a container where the fragments cannot land back in the display.
What to do
With flow off, inject a caustic paste or a commercial pest-anemone product into the oral disc. For a rock you can lift, the more thorough option is to remove it to a staging container and scrape the pedal foot off completely with a scalpel, then discard that water rather than pouring it back.
Source: Majano Anemone: Identification and Removal (Saltwater Aquarium Blog)