what is this coolant hose called? where can you get it and is this line breaking common?

 

that looks like the heater hose from the block to the firewall. no autoparts store had one, but you can get a "connector" and the appropriately curved hoses to make ur own. i think ive had 2 or 3 coolant hoses leak and/or crack. all the rubber stuff is pretty much dying by now.

 

Engine to firewall Heater hose http://www.mazdatrix.com/bhose2.htm

Oil drips down onto it making it soft, suceptible to bursting. Oil drips come from changing filters or leaking oil pedestal o rings

 

thats what happened to mine