The glowing spots are colonies of a bacterium which makes light. There are several species of bacteria which produce light. There will be a LINK here to a page devoted to growing and playing with such bacteria. It is said that marine animals obtained inland from fish markets never develop glowing spots, perhaps the surface bacteria are killed by some sort of dip. Dead fish found on the seashore may be tested, but animals direct from the sea give best results.
Some luminescent bacteria can be pathogens.
Some organisms have evolved in extreme water cycles. They grow in the rain puddles of spring and produce eggs or cysts which are able to survive in the dry dust of summer. These hatch when the next suitable spring rains arrive. Try collecting dried soil from the puddles of spring and see if you can obtain life from the dry soil several months later. Certain dryland rotifers which have survived 27 years in dry moss in dried moss herbarium collections.