Both love and war have been captured by scientists thanks to the development of an incredibly small-scale underwater microscope.
"Using the microscope we can see things as small as a tenth of the width of a human hair underwater," says study co-author Andrew Mullen.
Coral reefs can span hundreds of kilometres - the Benthic Underwater Microscope (BUM) brings the scientists in to view organisms as small as just 10 micrometres across.
The construction of the microscope even led to some somewhat-pervy behaviour from the scientists as they were able to observe coral polyps, the tiny animals which make up coral, "kissing" for the first time.
"We were definitely surprised by this interesting behaviour, and we are not completely sure of its purpose," says Mr Mullen.
"However we were not surprised that we observed novel phenomena with the underwater microscope as that was a significant motivation for building the instrument."
In situ image acquired using the 3x objective lens, in Eilat, Israel (Jaffe Lab for Underwater Imaging, Scripps Institution of Oceanography at UC San Diego)
But they didn't just see blossoming love - there was plenty of violence too, finally able to be observed at the uniquely-small scale.
There was serious science amongst the weirdness.
They found when corals of the same species were together, they were less likely to scrap it out than when it was two corals of different species - even if they were from different colonies.
"We think they might use some kind of chemical sensing to be able to recognize that their neighbour is of the same species," Mr Mullen says.
While brawling corals have been studied before, it's the first time the conflict has been seen in the natural environment, at such a small scale.
BUM was also taken to Maui, Hawaii, to study how algae grows on corals after a bleaching event, which has devastated corals worldwide.
Instead of the algae growing directly on the polyps, it grows between them.
In situ image acquired using the 3x objective lens, in Eilat, Israel (Jaffe Lab for Underwater Imaging, Scripps Institution of Oceanography at UC San Diego)
"This created a honeycomb-like structure of algae on the bleached coral's surface," Mr Mullen says.
The new microscope means scientists can study the coral polyps in the wild ocean, rather than having to take samples back to a lab.
"Previously no one has been able to obtain this microscopic view of organisms on the seafloor," Mr Mullen says.
"Additionally we can observe small fragile features that may be destroyed when bringing a sample back to the lab.
"This system has potential to be used to study a wide variety of important marine ecosystems and questions."
The research, also co-authored by Dr Tali Treibitz, was published in the journal Nature Communications on Wednesday.
Watch the video to see some hot coral-on-coral action.
Newshub.
