Specifically what did Grendel's mother do when she realized that Beowulf was in her lair?

Grendel's mother senses Beowulf in her lair. She catches him, but his chain mail protects him.

From the text:

"Quickly the one who haunted those waters, Beowulf is captured who had scavenged and gone her gluttonous rounds for a hundred seasons, sensed a human observing her outlandish lair from above. So she lunged and clutched and managed to catch him in her brutal grip; but his body, for all that, remained unscathed: the mesh of the chain-mail saved him on the outside. Her savage talons failed to rip the web of his warshirt. Then once she touched bottom, that wolfish swimmer carried the ring-mailed prince to her court

so that for all his courage he could never use the weapons he carried; and a bewildering horde came at him from the depths, droves of sea-beasts who attacked with tusks and tore at his chain-mail in a ghastly onslaught."