I've been playing space age with 0 evolution increase over time (killing bases still increments it). So I've been eager to work around biter bases and pentapods.
Biter spawners can all be blocked by a pattern like the image; surrounding them with walls or solar panels or pipes prevents spawning. (This is intended behavior.) What is not mentioned anywhere afaik is that this also seems to prevent biter expansion from that base.
The same is only partially true for pentapods! Small egg rafts only spawn wrigglers (at low evolution?), and it seems you can block them off as in the image above. I have yet to see one try to expand from a surrounded small spawner.
In both cases, surrounded spawners seem to absorb a small amount of pollution/spores, be unable to spawn anything, and sit passively. No attack triggered.
But (regular) egg rafts are different. They spawn stompers and strafers which can spawn and stand directly on top of the raft. I tried and failed to prevent this spawning by packing the space with spider-trons. Also, given enough time a surrounded egg raft will eventually expand (afaik, it seems to spawn a wriggler in a crevice which then attacks its way out. I've never seen it just spawn a wriggler).
Relatedly: Stompers and strafers can stand between tiled solar panels, but not walls. Stompers only damage buildings with each step if they are aggresive.
I looked into it last night.
No biter breeding on Gelba because the gravity is too high. No pentapod breeding on Nauvis because the gravity is too low.