Case in point ...
How could a clownfish possibly evolve without a fully-formed sea anemone in existence? If the defining characteristics of a clownfish is its immunity to an anemone's stings, then what would ever "motivate" this one specific type of fish to evolve this way? How many predecessor variations of the clownfish had to die off at the hands of the evil sea anemone before the current model evolved?
I think in these terms whenever I read a "scientific" article related to evolution. I try to imagine an ordinary spider spinning a web for no reason at all ... just waiting several million years for Charles Darwin to construct some flies and other insects to serve as his lunch.
Imagine the flies waiting for dogs to evolve so they could eat their poo.
No, not "an enormous pile of evidence", but maybe some in eukaryotes suggesting bits of DNA transferred between very different kinds of critters -- horizontal gene transfers aka gene hijacking.
Natural mechanisms for it include viruses which are today employed in state-of-the-art gene therapies.
Alberta's Child: "How could a clownfish possibly evolve without a fully-formed sea anemone in existence?"
No idea why this seems so challenging to you.
Occam's razor suggests the simplest explanation possible which would be some time in the distant past when those sea anemones had no poison and clown fish used them for cover.
Over time anemones develop increasingly poisonous cells and clown fish increasing immunity to them.
Any anemones without poison get killed by other predators and any clown fish without immunity get killed by anemones.
Coevolution is the term.