Concerning Praseodymium & Neodymium, where are these elements crucial?

Question

Would life on Earth be able to survive without them?

Answer 1

Uses of praseodymium:

As an alloying agent with magnesium to create high-strength metals that are used in aircraft engines.
Praseodymium forms the core of carbon arc lights which are used in the motion picture industry for studio lighting and projector lights.
Praseodymium compounds are used to give glasses and enamels a yellow color.
Praseodymium is a component of didymium glass, which is used to make certain types of welder's and glass blower's goggles.
Dr. Matthew Sellars of the Laser Physics Centre at the Australian National University in Canberra, Australia slowed down a light pulse to a few hundred meters per second using praseodymium mixed with silicate crystal.

Applications
Uses of neodymium include

Neodymium is a component of didymium used for colouring glass to make welder's goggles.
Neodymium colours glass in delicate shades ranging from pure violet through wine-red and warm grey. Light transmitted through such glass shows unusually sharp absorption bands; the glass is used in astronomical work to produce sharp bands by which spectral lines may be calibrated. Neodymium is also used to remove the green colour caused by iron contaminants from glass.
Neodymium salts are used as a colourant for enamels.
Neodymium is used in the strongest permanent magnets known - Nd2Fe14B. These magnets are cheaper, lighter, and stronger than samarium-cobalt magnets. Neodymium magnets appear in high-quality products such as microphones, professional loudspeakers, in-ear headphones and computer hard disks where low mass, small volume, or strong magnetic fields are required.
Probably because of similarities to Ca2+, Nd3+ has been reported [1] to promote plant growth. Rare earth element compounds are frequently used in China as fertilizer.
Size and strength of volcanic eruption can be predicted by scanning for neodymium isotopes. Small and large volcanic eruptions produce lava with different neodymium isotope composition. From the composition of isotopes, scientists predict how big the coming eruption will be, and use this information to warn residents of the intensity of the eruption.
Certain transparent materials with a small concentration of neodymium ions can be used in lasers as gain media for infrared wavelengths (1054-1064 nm), e.g. Nd:YAG (yttrium aluminium garnet), Nd:YLF (yttrium lithium fluoride), Nd:YVO4 (yttrium orthvanadate), and Nd:glass. The current laser at the UK Atomic Weapons Establishment (AWE), the HELEN 1-TW neodymium-glass laser, can access the midpoints of pressure and temperature regions and is used to acquire data for modelling on how density, temperature and pressure interact inside warheads. HELEN can create plasmas of around 106 K, from which opacity and transmission of radiation are measured.
Neodymium glass (Nd:Glass) solid-state lasers are used in extremely high power (terawatt scale), high energy (megajoules) multiple beam systems for inertial confinement fusion. Nd:Glass lasers are usually frequency tripled to the third harmonic at 351 nm in laser fusion

Answer 2

They fill a crucial gap in the Rare Earth group of metals. Since they are rare earths, they aren't necessary for life.

Answer 3

I think that neodymium is used in some type of laser.