The ones on the right are kinda cute imo

Was spore worthwhile?

Spore

More spikes is always the correct solution.

Too few phallic animals for that

Unlikely for there to be bubbly bits. These are bugs, so we know their shape because their exoskeleton (which is what fossilizes) is their shape. Fish haven't evolved yet

My first thought was "a brain with blades in it" and now I wonder how different our answers in a Rorschach Test would be...

I am not a biologist or really anyone with any authority on the matter. Just some guy who likes to read and think about all manner of subjects, so I cannot adequately explain anything here, but if you're interested in the why, it really boils down to the simplicity of morphological structures early in the development of life on earth, to more complex as evolution did its thing. That's not to say that evolution has a goal, just that added complexity often means greater advantages. Also, it isn't as though nothing similar to these creatures exist at all today. These basal forms were a prerequisite to the life we see in the oceans (and on land) today.

Definitely stay interested and read more about morphology and evolution in general! Fascinating stuff.

One of the big advances around then was being able to be an effective predator at all. It's likely one of the big causes for the Cambrian explosion was the arms race to not be eaten vs being able to eat your neighbors effectively.

Other tissues can become fossilized but it's less common as the conditions need to be just right. That's how we know some dinosaurs had feathers and what their skin texture was like.

Cambrian genera like Hallucigenia completely lacked bones and we have numerous fossils of them from deposits of shale. That's how we know what they looked like: tiny Lovecraftian horrors.

we know almost exactly how psittacosaurus looked:

thanks for introducing me to natures thigh highs.

Honestly 2 gets me. Hallucagenia!