LTA hiding and shrinking

[Jebecause]

Hello! While I am relatively new to saltwater aquariums, my partner has been doing this for years so he helped me get started on my own tank. That being said, he does not have a lot of experience with anemones. We recently got an LTA because I thought it was pretty (I know I should have done more research first but here we are and I need advice). I have 2 questions:
Firstly, my LTA seemed super happy and was in a great spot in the sand between some live rocks but it disappeared. This freaked me out as I recently saw an anemone get ripped apart by the pump and I never want to witness anything of the sort again. I gently moved the sand some with a net to see if she was buried and eventually she stuck a little tentacle out. She was the size of a dime when she reemerged when previously she had been about 5" across. Is this normal behavior to hide and shrink?
Second question, how often do I feed her? I have seen a lot of different suggestions from not at all to 4 times a week.
Thanks!!

 

[Gumbies R Us]

Do you have pictures of it?

For my BTA I usually will feed it once a week (I know its not the same as a LTA)