What is the term for the evolutionary resemblance of unrelated species?

Convergent evolution - unrelated lineages arriving at the same solution because the problem is the same. The camera eye evolved independently in vertebrates and in octopuses, and the octopus version is arguably better built, with the nerve fibres behind the retina rather than in front of it, so it has no blind spot.

The examples multiply once you look. Wings in insects, pterosaurs, birds and bats; echolocation in bats and dolphins, down to the same genetic changes in some hearing proteins; the marsupial thylacine looking like a wolf across 160 million years of separation; and koala fingerprints, indistinguishable from ours, evolved entirely separately.

Its significance is philosophical as much as biological. It suggests the space of good solutions is narrow, which is the main reason to think alien life might be recognisable - and the counter-argument, made by Stephen Jay Gould, is that rerunning the tape of life would produce something unrecognisable, with convergence a selection effect from us noticing the resemblances. Crabs are the standing joke: the crab body plan has evolved at least five separate times, a process biologists call carcinisation.