Strange clownfish behaviour?? Never seen this before !!

[TMH27]

Anyone got an idea what my clownfish are doing?
Not seen them do this before. Seem to be nipping at seal and glass?

They do a little swirling in ball very close to the bottom of the tank in their corner that they've claimed.

Any help is appreciated

 

[Tahoe61]

Challenging it's reflection.

 

[Shnetts]

normal clownfish shenanigans