grandmother's xmas cactus

i've had this xmas cactus for 35 years, and it was very old when it was given to me......unlike the specimens that i see in plant stores, much of it is brownish grey and hard, with stiff hairs.....yet, from this old growth, new, bright-green leaves, continually emerge, and
this year, the entire plant was covered with hundreds of flowers.......soon, it will grow dormant, to muster the energy for another
showtime......