That’s not necessarily a bad strategy, either. Most people, their home is their major asset, but you can’t really access that value to buy groceries in retirement. Take money out on a new mortgage on the inflated value of the house, buy groceries and pay mortgage with that money, and move in with the kids when/if the money runs out. The bank will take the house in the end, but leaving nothing to the heirs may be better than spending your last years living in your kid’s basement. The whole ‘reverse mortgage’ industry has grown up around just that plan.
Zebrafish need that rhythmic activity to form heart valves. They have unidirectional flow before the valves form, through some magic of resonance and pressure waves reflecting off arterial curves, and the resonance results in (IIRC) a stagnant spot where the valves will form. Do something to interfere with the mechanics and no valves form.