Ean Ean has bought for me a “superfood” based on Spirulina algae – apparently Kate Middleton eats it! It is sold as dry powder and I wondered if it was dead or alive. I put some in a cup of water for two days in the sun. In the photos below you can see algae cells – however lots of bacteria too which suggests that the algae are killed and the bacteria quickly take up residence with plenty of food available.
[You may also wish to view a following post where further work was done on this slide using COL, http://roslistonastronomy.uk/circular-oblique-lighting-col-on-microscopic-images-of-bacteria-and-algae]