Recaulking my shower?

My shower has tile walls and a fiberglass bottom. As far as I know (I have lived here 12 years) it has never been recaulked, and it is about time.
I started to remove the old caulk and found it is hard and grainy. Could it be grout rather than caulk? If it is grout, can I clean it up and put caulk over it? Or do I have to dig it out and regrout? Or is it not grout?
The rest of the walls are in pretty good condition, it is only where the base and the wall meet that are deteriorated.
Thanks. Thanks.
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<< I started to remove the old caulk and found it is hard and grainy >>
Get out your propane torch and see if a little sample will burn. Most grouts are low in organic material content and will probably not ignite. Silicones abused in flame will leave a white ash behind. Testing reaction to a paint remover with methylene chloride content might be informative. A grout would probably show littlle effect.
I'll leave the grout vs. caulk question to more experienced tile experts. HTH
Joe
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The material between the shower base and bottom row of ceramic tile is most likely grout. IMHO, the best course of action would be to remove the grout and caulk the seam with "Tub and Tile Caulking". Don't use grout because in time it will crack again. Removal of the grout can be accomplished fairly easily with a "Stanley" or "General" scribe that has a 90 degree scribe on one end and a straight scribe on the other end. Use the straight end of the scribe to put additional fractures in the grout and use the 90 degree scribe to pull the broken pieces of grout out of the seam.

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It is grout. It should remain grout for drainage reasons. Dig out the old, deteriorated grout and re-grout. The grout is porous and allows the moisture that goes through to weep down the underlayment and out the bottom over the lip of the shower pan. Many people just caulk but that traps the moisture and you will soon have an nice black line of mildew around the bottom the needs to be re-done every few months.
Inspector Dana

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