This 11 December 2017 NASA video says about itself:
In late December 2014 into early 2015, a submarine volcano in the South Pacific Kingdom of Tonga erupted, sending a violent stream of steam, ash and rock into the air.
When the ash finally settled in January 2015, a newborn island with a 400-foot summit nestled between two older islands – visible to satellites in space. The newly formed Tongan island, unofficially known as Hunga Tonga-Hunga Ha’apai after its neighbors, was initially projected to last a few months. Now it has a 6- to 30-year lease on life, according to a new NASA study.
This 5 February 2019 video says about itself:
The miracle outcrop known as Hunga Tonga has only existed for four years, yet is populated by hundreds of seabirds and flowering plants whose seeds were dropped there in bird droppings.
This 21 November 2018 video is about a visit to Hunga Tonga.
Translated from Dutch NOS eadio today:
With huge explosions and an ash rain that lasted for days, the island of Hunga Tonga was born in the beginning of 2015. The desert island in the Pacific Ocean is as big (or small) as Monaco and is a paradise for scientists and ecologists. It is already teeming with life.
“We were all like giddy school children”, NASA researcher Dan Slayback writes about his visit to Hunga Tonga. The excitement among researchers was great when it became clear that the very young island was home to [sooty] terns, barn owls and pink flowers in bloom.
“It started with the birds”, says ecologist Wieger Wamelink in the NOS radio program With the Eye on Tomorrow. For migratory birds, Hunga Tonga is a safe resting place without natural enemies. “They have been sitting there wonderfully. In the shit they leave behind, there are seeds and these have germinated, that’s where the plants come from.”
The ash rain has created a gray landscape with many trenches. A large inland lake betrays the location of the volcano crater. There is also a type of beach that consists of a clay-like substance.
“On Mars, you can see structures that resemble this island, and on Mars it is pretty sure that there used to be water, the soil is the same as on Hunga Tonga and we use that to see if plants can grow there.”
On Mars, there is no known life, and that was also not the case at Hunga Tonga. “That’s interesting: how are things? Which plants and animals and which ones not? And how fast is that?” Because the island remained undisturbed and virgin, scientists can fairly accurately measure how fast animal and plant species move in.
Hunga Tonga is located near the Polynesian Tonga archipelago, several thousand kilometers off the coasts of Australia and New Zealand.
This testing ground for Mars on Earth will not survive for long. Scientists expect Hunga Tonga to be swallowed by the waves within thirty years.