DSC04335

DSC04335

Observation - DSC04335. Description: DSC04335 and DSC04336 are pictures of a fungus growing inside and outside the wood of my hardwood front door - in a rural village in North West England. The current growth has developed in approx 2 weeks after previous growths twice sliced off by a razor

DSC04335 and DSC04336 are pictures of a fungus growing inside and outside the wood of my hardwood front door - in a rural village in North West England. The current growth has developed in approx 2 weeks after previous growths twice sliced off by a razor blade. Letter box cover shows scale.
What is the growth ? Where has it come from ? Is it possible to kill it and stop it growing again - or should I get a new front door ? Advice please...