What's on my glass?

[clearwatersaquarium]

Hello all! I'm still learning (after 8 years) & all of a sudden see a few of these on the glass of my reef and in the bottom of my d/s bags. What are they? And are they bad or good?

(I apologize for the repost but my pictures didn't go through the first time!)

 

[smh254]

Stomatella or Limpet snails there good guys

 

[Kentech5]

Definitely not stomatella. Those are limpets. Usually safe.

 

[clearwatersaquarium]

Yeah they just appeared out of no where! Thank you [emoji222]