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RE: Found this growing on a petri dish in the lab...
It may have been a bit dehydrated because the plate was old, but there were definitely microorganisms on it. Look at the morphology and compare it to just a dehydrated plate where the ridges and faults would be much larger. Also, I compared this dish directly to the same plates (LB+Cm @100ug/mL) that were vacant for growth; this one definitely had critters on it.
How could this be interpreted as anything other than a confluent lawn? Look at the first photograph where the agar is thin where there isn't growth and compare with the rest. It is evident there is a boundary for growth there the nutrients were minimal.
I'm not convinced. It's just hard for me to tell with these images. I've had plates that looked similar to this and they were just drying out. No microbial or fungal growth.
The patterns do indeed look neat, regardless.
Seen many dehydrated plates in my time, and this was certainly not one of them -- especially after I directly compared it to LB+Cm plates from the same batch that showed negligible rippling where they were beginning to dry out. Check out other photos of Paenibacillus to see what I'm talking about. Those branch points and patterns don't simply arise out of a dry plate; they would be much larger faults and not a separate hue/texture. This is definitely microbial growth on the surface. I can send you the original photos if you would like, but here is a couple enlarged images of the first photo:
![[crop large] 20171219_152603_HDR.jpg](https://steemitimages.com/DQmbJ8rvqWTpsAw3rReKUt13QPyd5LrmX8NMEg9MKpoBWLP/%5Bcrop%20large%5D%2020171219_152603_HDR.jpg)
Aaannd another. I will draw your attention to the boundary where growth begins to stop. Why would the dehydrated plate not see more of those patterns where the nutrients/agar is minimal? I now turn the skepticism to your interpretation of the data (in true scientific fashion)
![[crop small] 20171219_152603_HDR.jpg](https://steemitimages.com/640x0/https://steemitimages.com/DQmUvwQ3ApdvutvNvVtESf7G1i1R1GJRV54tuwhdKgoZ2Nv/%5Bcrop%20small%5D%2020171219_152603_HDR.jpg)
Right click and go to "View image" to see the photos in more detail...