Happens a lot. They seem to like to host in clams. Mine have hosted in my Derasa for quite a while now. Someone else on here posted this recently also. The clam eventually gets used to it and it's no big deal!
sometimes you wonder about clowns, mine liked to host my feather duster before I pulled it out. Now they just swim around aimlessly, completely unaware of the two beautiful GBTAs that I have.