Please identify this green jello organism

Question

I live in Okinawa, where the climate is sub-tropical, somewhat like Hawaii or Florida.

The green jelly stuff shown below is fairly common in my neighborhood, and has recently started to appear in my garden. I think it’s disgusting, and I’d like to eradicate it, so I’m trying to learn more about it.

It ranges from bright green to nearly black in color. It has the consistency of jello. I see no roots or any other structure. I notice that it tends to spring up after heavy rains.

My questions are:

1. What is it called?
2. How does it reproduce?
3. How can I prevent its insurgence?

Answer 1

Not doing well with searches involving your location, but it looks very like "Nostoc Commune" which is a cyanobacterium.

Image from the linked Ohio State University web page. Limiting phosphorous is mentioned under control, along with mentioning that it's hard to control/kill.

Another aspect that might help, based on their commentary, is that it may show up in, but does not cause, holes in grass lawns, but appears in them because light is available. You could try to provide plant cover to intercept the light, where your pictures appear to show bare dirt.

https://bygl.osu.edu/node/1580

As for how it reproduces, as a single-celled organism (or rather, by the time you notice it, a lot of single-celled organisms grouped together) any bit of it can make more.

Reproduction is solely asexual. In addition to simply producing new cells by cell division, they also produce akinetes, an enlarged cell that because it is tolerant of desiccation and other extremes it can therefore be dispersed through unfavorable space or unfavorable times

Quote from:

https://milnepublishing.geneseo.edu/botany/chapter/nostoc/

Answer 2

Wow. Thanks to the links provided by @Ecnerwal, I found that Nostoc Commune and related goops are truly fascinating organisms. A few random facts that deserve to be recorded here in an answer:

• It’s a bacteria, not a fungus or alga.
• Has existed for 3 or 4 billion years.
• Produced the first oxygen in the earth’s atmosphere, during the “Great Oxygenation Event”. This killed off a lot of existing organisms that were oxygen-intolerant, but precipitated the development of multi-cellular creatures like you and me.
• Found everywhere on earth, including Antarctica.
• In their dried-up crispy black state, they can survive for decades, and will come back to life when re-hydrated.
• Unaffected by Glyphosate, which is the universal herbicide in my neighborhood.
• Often called “blue-green algae”, even though neither blue-green, nor an alga.
• Many delightful names, including star jelly, troll’s butter, tears of lovers (Chinese), 发菜, ishi-kurage (stone jelly) in Japanese, and elulluchcha in Chile and Peru.
• Up until the 18th century, it was believed to come from outer space. Hence the name “star jelly”.
• Paracelsus came up with the name Nostoc. He said it looks like “excrement blown from the nostrils of some rheumatick planet”. Nostrils ==> nostoc.
• Frequently eaten in SE Asia and South America. So popular in Cantonese food that overharvesting occured, leading to government bans. Then, of course, some clever Chinese folks figured out how to make fakes.