Reply To: Techeiles 🔵❎🐌☑️🐟

“so all rambam (and k”m) means if something else besides isatis is domeh to techeiles it has the din of kala ilan (i.e. it isn’t techeiles, can’t be used for lavan on tallis shekula techeiles) But it doesn’t mean that in the times of the gemara they had something else. Just lidoros if they find something else it has this din.”

But we know that in the times of the gemara they had murex trunculus. So if the chilazon was some other creature and the murex trunculus was around and could dye the same color as techeiles (which we know it could because it’s the same color as plant indigo) then according to the kesef mishna the murex trunculus would be nichlal in kala ilan. And therefore when the gemara indicates that there is no blue besides techeiles and kala ilan, it wouldn’t be a raya that techeiles has to be from the murex trunculus, because kala ilan includes the murex trunculus.